For me it is most noticable when just hitting the fast forward button (not using gyro) - I have also notice that at least in these DVDs the counter in the top right doesn't seem to update very frequently (may have only just noticed as I am analysing the effect in more detail now!) I have been using 0704, 0710b2/3/4 and RC1 and 2 over the last 6 months, but have only noticed it since RC2, it definitely never used to happen ... although I confess that if it is limited to a subset of DVDs, and I don't use DVDs all that often, then I may not have noticed it in earlier versions. But it seems significant that I am seeing it frequently now. I will have to go through some more DVDs - extremely anecdotally(!) it may be more pronounced the further into the DVD I get, although that could just be coincidence or my imagination!
I will also have to check media files more extensively - I am watching one now, and it isn't doing it.... perhaps an absence of chapter markers? Again, the chapter relationship is entirely assumption at the moment.
Can't comment on the TV question, I am not running TV through my system at the moment as the jerky video is unbearable. On the few occasions I have done this AND recorded something it has always been VDR and I have had difficulty getting it fastforward/rewind at all - just seems to drop out and stop completely. Or do you just mean media files generally?
If the latter, x2, x4, x8, x16, x32 and x64 all work fine for me (there is no x12 that I have seen, not from the button press perspective, although I haven't checked using the jog/shuttle recently). But on video sources were the primary frames are far and few between (heavily compressed) fast forward and rewind always have difficulty as they have to jump from primary to primary, so you get this back and forward jittering for a second or two at slow speeds before it moves on to another pair of frames. Artifact of compression - but you should never see this on recorded TV that hasn't been re-transcoded as the frames are pretty frequent for DVB-T...