Not exactly sure what you're trying to do. Video is a series of frames with moving objects, so it's a very different approach to Photoshop. In Final Cut Studio there are various tools for doing compositing. Studio Artist can do things like this super well.
But I'd want to know exactly what you're trying to do. Can you be more detailed, or give an example?
here's a link to the snapshot of the video I want to correct. What I wanna do, if it's possible, is to erase the white thing that's on the upper side of the image. If it's possible I know it would probably be frame by frame right?
Thanks for your interest BenB
If you do know the answer please try to explain it in a way a 4 year old would, I'm really new to final cut
Roto-Scope! That's what you want to do. It's called roto-scoping. Several apps out can do that. Studio Artist, Shake, there's a "cheat" you could do in FCP.
Place a copy of the clip directly above itself. Apply a "Mask Shape" filter (Matte Bin) to single out a small space of the frame, something close to the white spot, but something to cover the white spot. And then a "Mask Feather" (same Bin) to make it soften out to the surrounding video on the track below.
Then, move the "Center" variables in the Motion Tab in the Viewer of that clip with the Mattes. Type in small numbers, what what it does, you'll get it, it's super simple. Now, move that masked out frame on top, so it covers the white spot area of the bottom layer video.
You'd have to maybe do some keyframing, or a lot. And it's a lot to explain. Basically what you'd do in Photoshop, more or less, but with motion keyframes. You'll keyframe the "Center" variable in the Motion Tab in the Viewer.
I don't do tons of roto-scoping myself, I have occasion to farm it, out but you want to look into applications that can do "roto-scoping". I'm drawing a blank at the moment, but there's several out there. What I explained above is a gorilla-video cheat. And can sometimes work ok. But you'd really rather have an application that actually does "roto-scoping". Go west young man, or, um, south, I dunno, whatever... roto-scope...
what you could do, since it is at the very top of your frame, is just increase the scale a little bit to crop it off the screen, I've done that before and as long as you keep it below like 120% scale, quality loss isn't an issue