Most videos offered are converted to around VCD or SVCD quality. So that's the quality you get. VCD = 352 x 240 (depending whether PAL or NTSC) & SVCD = 480x480
See description here: http://www.videohelp.com/vcd

Different encoders may be used. It depends on the quality of the ripper & converter & skills of user. Encoders used might be DivX, XviD, mpeg 1, 2, 4 or H.264, or 3ivx, etc. Quality settings will also apply to original conversion.

If you're having problems viewing, might I recommend VLC - (click on link) _ (choose nearest mirror site) as it has it's own in-built codecs for playback.