: The .mp4 file format was developed in the late 1990s. Any "1877" file found today is a modern digital upload, even if it claims to be a restoration.
: The Roundhay Garden Scene , the oldest surviving film. Sexy Girl (1877) mp4
A very short history of cinema - National Science and Media Museum look into these verified historical works:
For genuine early motion, look into these verified historical works: Sexy Girl (1877) mp4