exactly, and the hardest part or most frustrating part is when you screw up. You could be 10 minutes in, everything is going fine, and then your mind goes blank and you start babbling like an idiot. You can't really just edit that out, you gotta just do it over. Which is VEEEERY annoying.
But I mean, with gaming (assuming it's a traditional let's play) you kinda just have it or you don't. If you're naturally funny, your big obstacle is nerves, get over your nerves and be your funny self and you can make let's plays all day. If you're not though? Those videos can be... unsettling to watch...