What’s the browser you’re using ? and also please do:
glxinfo|egrep -i "^direct"
You’re looking for a line that says “direct rendering”; specifically whether or not it says “yes”. This will help pinpoint if you’re actually using your GPU or some onboard chipset instead.
With that being said, even assuming you use the latter, stuttering video playback in the browser is weird; if using firefox, out of curiosity: try to disable or enable hardware rendering (options > advanced > general), and try again. Switch it back to what it was when your test is done.
I did, years ago, it worked perfectly. This was when DX9 was an option for it though, but given since then dxvk / etc. came out the DX11 renderer should not be an issue. In fact I’d be surprised if the game didn’t run as-is without any tweaks.
I suggest using the gog version. appdb suggests installing vcrun2010 might be needed but again, test beforehand.