Motivated souls might wish to try changing the filename, stripping the metadata, clipping parts, and transcoding it (eg changing to a different bitrate) I expect they're matching files using filenames and/or checksums - ie that they'd recognise the entire video. I'd be surprised if they detect clips or transcoded copies, but it's entirely possible - they certainly have the ability to do automated transcription (ie they can create the text transcript then match words, phrases), as evidenced by youtube. Don't know whether it's practical to scan all of google drive. It might be.