>To me it's very different.
That's fine. It might be true for some, such as yourself, but I've never really felt anything similar. For me, unless I'm directly engaged in a hands on fashion with what it is I'm doing (so playing it myself, basically), then the various nice touches & details in the levels or other extra things in the design usually doesn't sink in and fly right by me. Watching another person waddle through a game, no matter how well it is they know it, has always been a very disconnected experience and will, personally speaking, never be a substitute for actually digging into and finishing it in real time for myself. As a result, that's why I almost always keep to watching footage from old stuff I've played already, or the random crap I have no interest in. Like having a TV running in the background with the sound turned off. All the while staring off into space in an unconscious fugue simply because you got nothing better to do. There's exceptions, of course. Pathologic & The Void being two examples.
I actually just remember how I watched, mostly, all of CannibalK9's excellently informative & relaxing playthrough of The Void a long time ago, so just a bit of an addendum, I suppose. I'd still like to play it for myself someday, but sometimes just watching can be a nice half-measure. Especially for weird, esoteric ordeals like the kind Icepick Lodge offers.
CannibalK9's Void playlist: https://www.youtube.com/watch?v=k_wZZ8SaLVU&list=PLB8F47C6867017A55
SulMatul's Pathologic playlist: https://www.youtube.com/watch?v=I5Y4Zjp_5S0&list=PLO6dQRhxbNE8X4VVY7nMEw8bc3DmoV0ev
I do find it odd how I'll often never notice the soundtrack when I'm playing a game. One example of this being beating Hotline Miami 2 and then hearing Le Perv & Roller Mobster a few months later and thinking I was hearing them for the Post too long. Click here to view the full text.