Cave in Plymouth unknown to me

[mrodoc]

Whether it is actually a cave I don't know (might be evidence of mining) but it certainly intrigued me. I found this video quite by chance (it popped up when I was looking to repair a scratch on my dome port lens) and the location is not described. Anybody know anymore

 

[The Old Ruminator]

Looks most interesting Peter. Hope you locate it.

 

[mrodoc]

I wanted to contact the chap who posted it who obviously lives in the area but the only contacts are social media I have plans to use.