Right, and at 480x272, the resolution of the PSP is a little more than 1/3 of a DVD's 720x480, making the UMD have the same storage capability of a single-layer DVD as far as movies go, which would be around 2 hours.
Yeah, but PSP uses much more efficient codecs (MPEG4, H.264, etc) than DVD's MPEG2, so the comparison isn't valid.
Also, there's been some buzz lately that internally the UMDs are 720x480, and are scaled down to fit the PSP screen. If this is true, you'll likely see other UMD movie players with more resolution at some point.
Perhaps, but even with the improved codecs, many of the initial UMD movies has issues with encoding artifacts and color smears and such, although some of that may be due to the LCD used too, I guess. But as far as answering whether 13 half-hour (22 minute?) episodes of Sanford and Son can fit on 3 UMDs, I think that question was answered.