Switching to the x86-64 branch of Garry's Mod

For video playback to work, you need to be using the x86-64 chromium branch of Garry's Mod. To use this:

1. Close Garry's Mod
2. R-CLICK Garry's Mod in Steam and select Properties
3. Navigate to the Betas tab
4. Select "x86-64 - Chromium" from the dropdown
5. Close the popup and wait for Garry's Mod to update