Browsers are h.264 only. Best option is to use a client that direct plays Mpeg2 like your phone (Roku, Shield, Firetv). If you had a Windows/Mac Laptop and used Plex Media Player you would get excellent results.
Radeon video is not currently supported by Plex under Linux. Leaves you Nvidia or waiting for the Intel Xe GPU card due next year. Would still be a delay to scrub through the program.
You could optimize after recording to browser which would create a copy in h.264 or take whack at fine tuning the commercial removal settings.
