[Galaxy Tab 10.1 Android Development] decatf:
Guide to flashing the bootloader is in this old thread. It only works for unlocked bootloaders. There is no other option if the bootloader is locked.

http://xdaforums.com/showthread.php?t=1130574

The GPU is overclocked. It always has been. I am using a kernel forked from twa_priv. The history of the kernel is like this: pershoot > twa_priv > decatf. All features exist since first custom kernels by pershoot.

The video playback issues are not likely to be solved from our end. It is probably a lot of problems than just one. It will get worse as time goes on. The video drivers and video codecs have been the same since ICS, Jellybean, and Kitkat. There is no other driver that was ever available. The kernel has more or less been the same since ICS, Jellybean, and Kitkat. I keep mentioning these because people seem to think this is where it can be fixed.

What has changed are things beyond our control.

Android frameworks change

- Android frameworks are designed for current generation devices. Google cares little about retaining compatibility for old devices.

- There are two new dynamic streaming features in Android frameworks which are not supported by this tablet. Instead of failing completely they have allowed it to continue despite not having these features.

Video services have changed.

- Videos are encoded with more demanding requirements.

- Servers are using newer dynamic streaming technology.

- These are server side things. We cannot change this.

Apps have changed

- Apps can use the Android video playback engine (AwesomePlayer and Nuplayer in the Android frameworks) or their own internal playback engine.

- Youtube is not open source it uses it's own internal playback engine. We cannot see what has change or fix anything ourselves.

- Chrome videos crashing. It uses it's own internal playback engine. Same as above, we cannot see what has changed or fix it ourselves.

- Videos on other apps. If the app is open source then you're free to study the code and try to determine if it was some change in the app.

Youtube freezing issue

The Youtube video freezing issue affects a lot of different devices and nobody seems to know exactly why. Google does not seem to care to fix it. Just do a Google search on it. Some older versions of the Youtube app might work better for reasons unknown because we don't know what they've changed in the app.

Tegra 2 is just plain slow - A demonstration:

The truth is the Tegra 2 hardware has always been bad at HD video playback. It is slow hardware. No software can fix that. Here is a quick demonstration.

Two HD videos. Same resolution (720p). Same filesize (70MB). Same bitrate (10mbps).

Jellyfish-Baseline_3.1_10mbps.mkv

Jellyfish-High_3.1_10mbps.mkv

Play both on your tablet at 1Ghz CPU speed. One will play fine and one will lag a lot. Why? The former is encoded in Baseline profile x264. The latter is encoded in High profile x264. The Tegra 2 cannot decode High profile videos smoothly. Which encoding does Youtube use right now? High profile.

(Yes, overclocking the CPU will help in the case of this demonstration but I've used a lower bitrate to save bandwidth. At higher bitrates even overclocking the CPU will not help High profile playback.)

Those two videos are constant bitrate samples. In real applications you will encounter variable bitrate videos which is why some videos seem to work better than others.

In summary

This device has always had half broken x264 HD video support. It seems to have gotten worse because 1. videos are being encoded with more demanding requirements and 2. HTML5 video has gotten more popular which means you are running to into more apps and websites which rely on x264.

There are specific parts of code in old Android frameworks (in AwesomePlayer) marking the Nvidia HD video decoders as slow and running specific hacks to deal with it. This is an example of the kind of workarounds that are no longer been retained by Google (in Nuplayer) and likely not by app developers. Tangentially, it is a reason why some other video playback apps like XBMC have not bothered to support Tegra 2. It's half broken and too slow.

No, I am not intentionally ignoring the issue. Considerable time has been spent by myself and others from what I have seen in trying to find ways to resolve it. If it could have been solved probably would have by now.