Been using chrome with autoplay disabled and max width 720p without any issues here.
So, downloaded a FF X Remaster video off gamersyde so I could do some tests with the latest script by Skyfireblaze (great work man, keep it up).
First off I tried 720p with 2Mb bitrate limit (no audio) and the end result wasn't satisfactory, kinda choppy.
Then I set it to 720p with 3Mb bitrate limit (also no audio) using VP8. This is the result at 3.74MB
http://a.pomf.se/cbygvl.webm
Looked good, but maybe if I lower the quality a bit and keep the bitrate it might get smaller.
Then I tried VP9 with the same settings. This is the result at 5.28MB
http://a.pomf.se/ewmlzh.webm
Looks great, although the size difference bugged me so I went on to check the media properties and it seems the bitrate for this one was average 3.6Mb, no idea why it did not comply with the limit I had set. But this explains why it is bigger (and looks better).
Will keep fiddling with it, been fun.