To everyone, if you could describe the steps when you have an issue with as much detail as possible.
Even better, make a movie. Either use screencastomatic or jing to record your windows session as you duplicate what you did OR use your phone and record a movie.
It makes it so much easier for us to understand.
you should be using ffmpeg to create thousands of files
ffmpeg -i frozen.mp4 -r 20 -s 50x50 f-%d.png
will take frozen4.mp4 as an input
-r 20 says to resample the movie to 20 fps from whatever it is currently running at (normally 30fps)
-s 50x50 resizes the movie to 50x50 pixels
output files created will be
f-1.png
f-2.png
...
f-9999.png
be sure to put in the dash as i think i look for this pattern to start "something"-1.png
go to the pictures effect and give the first frame picture, f-1.png
xlights should start flipping frames