try_seek is impossible to use with non-constant speed

[dvdsk]

It takes the current speed into account but not what it has been the past t seconds. So if my speed was 0.5 and now its 2 try_seek will assume it has always been 2.

Correcting for this requires speed to keep track of all the speed changes.

possible fix:
Make speed's try_seek behavior configurable. Or for now disable all the fancy stuff.

This breaks the current API but I would say the current API is so broken its okay.