Improve YouTube playback on older video cards

If you have an older graphics card (like the GeForce GTX 750 or the Radeon RX 460 for example), you may not be able to decode VP9 video from YouTube in hardware. This is the case if the "Video Decode" section of the GPU performance tab in Task Manager is showing 0% during playback:

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In order to change that, you have to enforce the H.264 format, which is natively supported even in very old cards like the GTX 260 or the Radeon HD 3000 series.

In Firefox, this is done by calling about:config and changing the setting "media.webm.enabled" to false.

If done correctly, you will see the "Video Decode" section showing some activity during playback:

 

NB: with older nvidia cards, there may be a problem with newer drivers getting the DXVA hardware acceleration feature working. It is advisable in this case to go back to an earlier driver, like version 353.62
In case you don't get the GPU tab in the Task Manager with older drivers, you can still see this information by checking the "Video Engine Load" in GPU-Z.

How to apply DRC to DD+ Audio

 You may have a 5.1 Dolby Digital Plus (E-AC3) audio track lying around, that you want to apply Dynamic Range Compression to while transcoding it?

Well, the eac3to tool does not seem to help here, so here is an alternative: use FFMPEG!

The command line would look like:

ffmpeg -drc_scale X -i input.mp4 output.wav

where X = The DRC ratio you want to apply. 2 or 3 is a good value here.

Now you can take that WAV output and transcode it to whatever format you like :)

Beware of Stock AMD Ryzen coolers!

 There seems to be a problem with the thermal paste that comes with Stock AMD coolers, which leads to the CPUs being pulled off their socket once you want to replace them, as it tends to become like glued:

So make sure you remove the thermal paste that comes with it before installing it, and use some HQ paste like the ones from Arctic.

It is also always a good idea to let the CPU run hot with some Prime95 load for 15 minutes before replacing it, as this makes the paste a little bit more fluid.