What emulator are you using?
EDIT: I'm an idiot, will post a tutorial soon. I assumed there were large differences between snes9x 1.43 movies and snes9x 1.51 movies.
EDIT2: you can't change the rerecord count with QuickHex. You can change the rerecord count with a standard hex editor (for example HXD). For snes9x movie files, open up the movie file in the hex editor, and go to the offset 0x0C. The rerecord count is stored there in hex. (see photo)
let's say I want to change the rerecord count to 1337. Well just type that into calculator.
and then select "hex"
see how the number has changed from 1337 to 539?
so now, we add as many zeroes as wee need to make the number of digits 8. so
539 (3 digits)
becomes
00000539 (8 digits)
Then we separate the digits into groups of two, so
00000539
becomes
00 00 05 39
and then reverse the order of the groups. so
00 00 05 39
becomes
39 05 00 00
Then we just use the hex editor to change the rerecord count to tho new number. Then you should save.
when you open up snes9x again, and open the movie, the rerecord count should have changed.
I don't recommend trying to use this technique to boost up your rerecord count for a movie, since that would be irresponsible. I would say, only use this if you want to add rerecords if you are hexing in a movie, to more accurately show the rerecord count, or use it to do what I did, and change the count to an interesting number.
