The clip is from a DVD extra of the Charlie Chaplin film The Circus. In the clip, a woman is seen in the background, holding to her ear what appears to be a mobile phone.
Speaking to the BBC, George Clarke said: "As I sat back to watch it I realised in the first 30 seconds there's a lady strolling by with her hand up to her ear which looked quite familiar in today's society.
"So I wound it back and watched it again, zoomed it in and slowed it down and got other people in to check it out. Everybody had the same reaction - it looks like she's talking on a mobile phone."
Since the video was posted on YouTube, it has received 1.5 million views and more than 10,000 comments.
Clarke added: "My initial reaction was, 'That's a mobile phone - they weren't around then.' My only explanation - and I'm pretty open-minded about the sci-fi element of things - it was kind of like, 'Wow, that's somebody that's went back in time.'"