macOS Desktop App to Grab Videos from Web

I need 25 videos and 11 pictures automatically gotten and compiled into a video at the push of a button. Some videos will need element interaction to start. 3-4 video copies will need speedup before or during compiling. Some videos will need to be cropped either during copy or post. Each clip will have a screen title. I have all the endpoints and a sample video. I work off a Mac running El Capitan and would like the end movie to be .mov or .mp4. I need a real basic gui with a place to change a auto generated filename and a start button.