FF/REW speeds

[Syberia]

Something that's been bothering me lately...

I was under the impression that the smooth FF/REW feature would allow me to choose the speed of my fast forwarding/rewinding like a DVD player, for instance press it once for 2x, again for 4x, again for 8x, and so on. A Google search on the issue seems to indicate that that's the way it does work. However, in my case, the only speed I get no matter how many times I press the FF or REW buttons is 4x, with no other options. Does anyone know how to fix this?

Also, the "play while rewinding/fast forwarding" only seems to work on certain files. On some unknown-codec .avis, it works perfectly. On the 720p mp4s I've tried, it moves the cursor along the timeline at 4x speed (since that's the only speed I can get it to work at), but the video freezes until I press play again. And the weirdest thing is, on videos that Sage itself recorded off my TV, it also freezes until I press play again. You'd think that a Sage feature would be compatible with videos that Sage produced...