[Tets]

I don't understand why people claim that compressing UMD dumps can diminish the graphical quality, it's an outright lie. ISO compressors can't magically find all the files that textures are stored in and lower their quality. CSO is more comparable to zip or rar archives than mp3 audio or jpg images. Everything that goes in comes back out exactly the same, and the only disadvantages are potentially longer loading times and more CPU cycles spent on decompression.

But if you're experiencing things like the flickering video that Palmtree reports, you should use a compressor that will allow you to leave video files uncompressed. There's no point in compressing them further anyway.