Repository: youtube-dl
Issue: skipping video download also skips non-video post-processing actions
Labels: bug

### Make sure you are using the _latest_ version: run `youtube-dl --version` and ensure your version is _2016.04.01_. If it's not read [this FAQ entry](https://github.com/rg3/youtube-dl/blob/master/README.md#how-do-i-update-youtube-dl) and update. Issues with outdated version will be rejected.
- [x] I've **verified** and **I assure** that I'm running youtube-dl **2016.04.01**
### Before submitting an _issue_ make sure you have:
- [x] At least skimmed through [README](https://github.com/rg3/youtube-dl/blob/master/README.md) and **most notably** [FAQ](https://github.com/rg3/youtube-dl#faq) and [BUGS](https://github.com/rg3/youtube-dl#bugs) sections
- [x] [Searched](https://github.com/rg3/youtube-dl/search?type=Issues) the bugtracker for similar issues including closed ones
### What is the purpose of your _issue_?
- [x] Bug report (encountered problems with youtube-dl)
- [ ] Site support request (request for adding support for a new site)
- [ ] Feature request (request for a new functionality)
- [ ] Question
- [ ] Other

---
### If the purpose of this _issue_ is a _bug report_, _site support request_ or you are not completely sure provide the full verbose output as follows:

Add `-v` flag to **your command line** you run youtube-dl with, copy the **whole** output and insert it here. It should look similar to one below (replace it with **your** log inserted between triple ```):

```
$ youtube-dl -v --skip-download --write-sub --convert-subs srt --all-subs https://www.youtube.com/watch?v=sLEdi49XEhA
[debug] System config: []
[debug] User config: []
[debug] Command-line args: [u'-v', u'--skip-download', u'--write-sub', u'--convert-subs', u'srt', u'--all-subs', u'https://www.youtube.com/watch?v=sLEdi49XEhA']
[debug] Encodings: locale UTF-8, fs UTF-8, out UTF-8, pref UTF-8
[debug] youtube-dl version 2016.04.01
[debug] Python version 2.7.6 - Linux-3.13.0-83-generic-x86_64-with-Ubuntu-14.04-trusty
[debug] exe versions: none
[debug] Proxy map: {}
[youtube] sLEdi49XEhA: Downloading webpage
[youtube] sLEdi49XEhA: Downloading video info webpage
[youtube] sLEdi49XEhA: Extracting video information
[youtube] sLEdi49XEhA: Downloading MPD manifest
[info] Writing video subtitles to: The Beauty of the Dinner Scene-sLEdi49XEhA.en-US.vtt
[info] Writing video subtitles to: The Beauty of the Dinner Scene-sLEdi49XEhA.en.vtt
```

---
### Description of your _issue_, suggested solution and other information

Using the `--skip-download` option seems to skip post-processing options, or at least the `--convert-subs` option.  The other post-processing options are related to the video, so it makes sense that they'd be skipped, but `--skip-download` is a handy feature for downloading subtitles but not the video (particularly for really large videos that you've already downloaded and don't want to download again), and post-processing options for the subtitles should be processed.

Either that, or for the sake of internal consistency, `--skip-download` should also skip downloading subtitles.  Perhaps the ability to download subtitles but not the video was an accidental feature?  Maybe `--skip-download` was always intended as a dry-run feature, to not download anything?  Personally though, I would prefer there be _some_ way to download just the subtitles and post-process them.

In the example command above, the video has subtitles in vtt format.  Without the `--skip-download` option, the vtt subtitles are eventually converted to srt.  However with the `--skip-download` option, they're left as vtt.