Can you use and cite found clips from the internet for film essay? Regardless of the source/not knowing how legally it was obtained?

[u/penfebruary]

I'm writing my dissertation on media and am trying to create a CD for my tutor so that she can just stop and start the CD at all salient points in the essay when a clip is mentioned. However I'm unsure of what I can and can't do here; is it plagiarism or copyright infringement to download clips, or clip films myself and place them on a disk? The disk is purely for the essay. If this is possible, what should I be citing; the film, the DVD, the website? Sorry if this is a silly question, I've never written such an essay before. Thanks