Can't import video into Android

So it's 4 in the morning, and I'm banging my head against the wall trying to get a video onto the app on my phone after much frustration trying to get the timing right on Windows 10 which just stutters badly, and doesn't allow more than around 30 seconds of adjustment which resulted in more editing time of my Midi track. (Windows 10 refuses to render, so I've used my phone for the final render to get around this problem). So I've used the most basic filename- Poulenc.mp4 but after using the file import, it says please choose how you'd like to import this video file: video%3A139469 And then says video%3A139469 is a file type that is not currently supported by SeeMusic. I've tried placing the file in DCIM on internal storage, but no joy. I've also tried using a file explorer app outside of SeeMusic to then open it with SeeMusic, but I get the same problem. Please advise. Bob