How to playback faster than 1.5 speed on PS3?

[Nadahar]

I think you're out of luck if the renderer doesn't support it. Assuming that you're not transcoding, the renderer actually receives the video file and controls playback. UMS has no impact on this. If you're transcoding, I can't say if it would or wouldn't be possible, but it would at least require some special code to achieve this - IF your computer is able to handle the transcoding at that speed.

I don't know why you prefer watching things in this speed, but you are probably better off figuring out how to user FFmpeg to convert your videos into "fast" versions.