So I'm practicing on a video of my siblings and have a problem with some reflections in a window so I was just going to replace the window in the frame from a different frame where the reflection is messed up with one that its fine, but I can't seem to remember how to do that.
is the camera moving or on a tripod? if it's not moving you could place the video with no reflection on top of the original video and mask the no reflection video on top. if the camera is moving there maybe tracking involved (how critical are you?)
to give you the most efficient advice we would need to see the video of the footage with the reflection.