Wow, those are questions that make you seem very interested, which makes me want to answer.

1) The company I started working for already had the software that was the de facto industry standard for DVD authoring, Scenarist. When I started, the software was running on Windows NT. It wasn't until a bit later before I learned that it was the first version to run on Windows. It was dog slow. Things improved dramatically with the release of Windows 2000. Apparently, the previous version was being run on some form of *nix, and required a lot of text file manipulation. It wasn't until I got much more advanced before I went back to manipulating the text file versions as well myself. But for day-to-day stuff, the UI was what I used.

2) I used lots of stuff that was ancillary, but nothing proprietary or open source other than awk/sed/grep and shell scripts written using those on the aforementioned text files.

3) I started programming DVDs in 1999, and continued working shiny round discs until 2006. By the time I left, the company had garnered a few awards, had grown to 10 full time employees with multiple DVD authors, and an award winning graphics team, and was quite an interesting place. Haven't found a company since that compares.

4) I got into it by luck really. I was working in the editing department of a film post production facility. I was the youngest person there that was too eager to do things that nobody else wanted to do. That meant most of that "computer shit". This was the time when dinosaurs roamed the earth. 1" tape machines, reel-to-reel Nagra tape decks, and all of the other analog/digital cassette tape decks were within arms reach in the machine room that was my workspace. Clients eventually started wanting these new fangled Video-CDs which required computers (gasp!). So I started capturing MPEG-1 videos. There was another small company that specialized in interactive CDs using the old Macromedia Director software that we would contract jobs out to. This company eventually moved into a small bit of workspace within our company's space as co-op agreement. We'd get discounts on their services as well as advertise being able to do those services to our existing client base, and they would get use of our video equipment which expanded their input capabilities. I then became the liaison between the two companies. When my time at the post house came to an end, this company contacted me a week later asking me to have lunch. I started working with them a week later.

5) specialized hardware is a tricky question. To the industry, most of the hardware was typical, to someone unfamiliar, it's all very specialized. By that, I mean that the SD master tape format was Digibeta and was not uncommon to have multiple racks with multiple decks in each rack. Each digitbeta recorder original MSRP was close to $80k. When HD equipment came out, the HD-SR was the top machine, and it was $120-150k. We'd receive SR tapes and take a downconvert out of it for DVD use. So, that kind of stuff probably sounds specialized, but was typical (for well funded outfits). This is why the co-op agreement for this company was such a good deal for this smaller company. After the video equipment, there were full length PCI cards for encoding to MPEG2. Software encoding was years away still, and playback from tape to an expansion card was the way it was done. Just like with software encoding, there were "quick" one pass encoding, and then there was the slower 2-pass encoding. Both passes were done with real time playback from a master format tape machine. This made things very expensive as you were paying for the deck by the hour. Once the first DVD recorder came out at $15k, it could only record 3.5GB. Oh, Scenarist went for about $20k at the time as well. For motion graphics for menus, we were using some version of a Targa card to capture uncompressed 10bit data (ugh, the files were so large for the time). There were other pieces of equipment that were again normal for a post facility, but kind of specialized other wise. There were boxes from Teranex and (I'm blanking on the name of the other boxes) that did things like standards conversion from NTSC<=>PAL, noise reduction, etc. The toughest part was to take film original content with a 3:2 pull down pattern into it and feed it as a 24 (23.976) frame rate to the encoder for a progressive encode. This got much easier when software encoding came about and we could process data that way. This became very viable for us when Apple released the first Mac Pro Intels. We used Final Cut Studio to capture the footage, and would then reboot into Windows to use the MPEG-2 encoding software. We tried using Adobe Premiere to capture while in Windows, but their software refused to capture multichannel audio sources as discrete audio tracks. It would only create multichannel interleaved sources. It also had some other pain points for us like only capturing as AVI (shudder). I wrote a ranting review of the decision process of switching to Final Cut on the DVD mailing list that got a lot of attention. Including a rep from Adobe that contacted me through the HR department to get permission to chat to me (which was interesting of being a "correct" political move to be made). After going complaint by complaint through the rant, the rep said, you have some good points. "Would you consider switching back to Premier if these issues were resolved". They were ultimately resolved by Apple folding that space with the release of Final Cut X.

6) I was hired as employee #3 in a full time position. The owner was from England, and ran it in a very English manner. Fridays, we would all go out to lunch together, and was only expected to be in the office long enough to sober up before heading home. We did all sorts of work, but never for feature content from studios directly. We weren't on their radar since we were not located in the "cool" part of the country. We did a lot of corporate work. We did land a couple of film distributors to get back catalog feature titles or imported titles. We did a lot of DVD games. One of these was a massive 18 month long project. We knew from the beginning that the project ultimately wanted to be released as NTSC and PAL, so we designed all of the graphics in HD. Early on, the decision to solely focus on the NTSC release was made. This was a complex disc with animated graphics and a list of 300 questions that were meant to not repeat unless the disc was restarted. The programming was quite a challenge, and there were no graphics ready to be used in testing. So a series of place holders were created with the code for each question as big block white text in Impact font on black background. Then the reveal, then the answer all in similar style. Once the programming was completed like this, the disc was sent out to a 3rd party testing facility that had every single DVD player that was available to the public. Not every DVD player was the same and had different features/capabilities. The cheap Apex players didn't actually have a random number generator. It had a randomized list that would give a random appearance, but the random was the same each time. This made for poor game experience as you'd just remember the patterns. Once the programming was approved by 3rd party, the disc was ready for graphics. The UI for the system had a way to point assets to a new folder, but it was very very very very slow. Instead, we exported the programming to a text file, created a shell script using awk/sed/grep and processed the very large text file in <15 seconds. That new file was re-imported back into the system in less time than the UI would even be a fraction of the way of updating to the new asset location. The final week before the project was due to be delivered, the call came in asking if we could go ahead and deliver the PAL version (who didn't see that coming?). Graphics team already had been prepped for this. These guys (it was one guy and one gal) that had programmed the crap out of Adobe After Effects with the javascripting built in. They fired off one script, and it queued up renders of the HD->PAL exports. When those were done, we reran the awk/sed/grep script tweaked for the NTSC->PAL conversion and in <30s (it took longer as there were many more things to change), we had the PAL version of the programming. We delivered 2 days after the ask which was 2 days before deadline.

7) Now, I specialize in prepping old content that's "in the can" which is basically back catalog content that people are trying to monetize on the various streaming platforms. What I'm doing is way more in depth than that, and actually pretty cool stuff (if your a video engineering nerd). Otherwise, I'm just helping make the infinite scroll of content on your streaming platform of choice get that much longer.