The only reliable method I have found so far for making my videos look good on YouTube is to use input files that are formatted 640 x 480 uncompressed AVI. I have tried capturing video from my video recorder in MPEG, VCD, SVCD, etc. but I usually end up with a problem with either painfully slow previewing in Premiere Pro (1.5.1) or video quality issues.
I would much rather work at 352 x 240 for several reason. The files are drastically smaller which makes life easier from a rendering and preview speed point of view, in addition to avoiding the aggravation of handling massively large files. 640 x 480 uncompressed AVI works out to be about 1 GB per minute. If I am creating a video from a large body of video clips that I intend to add a lot of video effects to, then working at 640 x 480 becomes a painful experience on my 3.2 GHz Dell with 1 GB of memory.
Now 352 x 240 looks just fine when I render to that size. The problem is that YouTube automatically displays videos at 425 x 350. There's an "original size" button but nobody presses it. I haven't had much luck with the quality of the 352 x 240 sourced videos when displayed at YouTube's default size. However when I upload videos that are sourced and rendered at 640 x 480 then everything looks great because 425 x 350 is a downsizing. But when my 352 x 240 video is displayed at 425 x 350 there is a big quality loss.
I have tried different formats from Premiere Pro such as Windows Media Format (WMV) and others but that didn't help. I even tried rendering to uncompressed AVI and then using the DivX encoder but the results were the same. Even Dr. DivX's smoothing and masking filters didn't help.
Pardon that long preface but now you know my situation. Here is what I want to know. Are there any tips, filters, tricks, or post-processing techniques that would help me create videos that upsize well?