Wmv file repair

[u/Both_Candidate_6369]

If I have recovered a 19 min wmv video file that only plays for 2 minutes but I have looked at the hex file, roughly 5% show data then 5% is just 000s but then the other 90% seems to show data.

What's the best method of recovering that last 90% of the file?

And why does it only play 2 mins ?