If you're trying to prevent any seek from happening until the whole file is downloaded, you could listen for MediaPlayer's "bytesLoadedChange" event, and only enable seek when bytesLoaded == bytesTotal. But if you're trying to prevent seeking beyond the current download point, OSMF currently doesn't support this, though it probably should. I recommend you file a bug on this to make sure we address it (and reference this thread).
The fix would involve modifying NetStreamSeekableTrait.canSeekTo to take into account how much data has been downloaded, and return false if the requested seek point is outside of that range. This would allow player developers to call canSeekTo prior to seeking, and only attempt the seek if canSeekTo returns true.
Has this been bugged? I get the impression from the OP that they would not know how to submit such a bug.
edit: I couldn't find the bug, so I added it. Hopefully it's not a duplicate.
Excellent, thanks Avi!
Thank you everyone!
I am sorry that where I can find the filed bug and when it will be useful for us all.
Thank you for your intelligent work!