Some good points frog, but to the tatoo thing, if you properly take care of your tatoos when they are new, they will still look fresh as the years go on. I'm not 70, yet, but, I've had my tattoos for over 20 years and they still look as fresh as when they were new. That's because I read up on how to care for them before i got them. So..... IF he took care of his tattoo, then you can't prove it by the look of the tattoo alone.
Sun shining behind the old man.......... yes, makes it look like they were trying to hide something, for sure. I can agree with you there. It does seem quite odd.
However, looking at the video closely, these 2 men have exactly the same features. Shape of the nose, shape of the head, smile, eye shape, etc. Yes, this could be a hoax played with the guy's grandfather, but the men ARE identical from what I can see. They even move the same.
Yes, there are a lot of questions that need to be answered in order to get a better picture of what happened (whether it's hoax or real) such as how he got back, like you mentioned above. Why did he only film the man and nothing else? And if he did film anything else, why didn't he show those videos too? If it was me, I'd've taken as many videos and pictures as I could and I would've posted them all. He said he was living in the same house at 70 years old, why didn't he show the house from the future? Wouldn't that have been great proof?
Because these things are lacking, at this point, as great as the story is, I have to call it like i see it at the moment. Without further proof, I can't believe it. I can take it as an inspiration and hope that it happened, but based on sheer evidence, there is NO proof.
If this DID happen though, can you imagine what this guy was feeling and thinking? Holy crap! Must've been overwhelming!