Think I got the vids (all MP4) from emumovies, ages ago. I'll give the standalone MaLa player a go - I see the download page has a link to a codec pack, so will try that, too.
However, I have a spare win7 PC with an ATI 4350 installed, and videos work fine in MaLa on that, after installing the Klite codecs. This leaves CRT_emudriver as a possible cause for loss of framerate in videos? I don't know, TBH. Especially as vids played fine when I was using an older version of CRT emudriver.