Found this intriguing early clip of unknown origin of America doing “Tin Man”, and was reading the many posters commenting on the dubious skill of the bass player.
My questions- who is the bassist, and what is he wrong or different? The record has an awesome bass line IMO and while I know nothing about music, I agree the guy in the clip is off in some way. Is it he doesn’t know the song? Is he a good player trying something new with it? Is it he isn’t very good? Stoned?
He sounds a little out of tune, and if I were playing the line I would played it a lot more fluid with more runs and sustained notes and less of that bossa-nova eighth-note pattern. It doesn’t fit the song as well as it could and it’s a bit basic and elementary. Also, the recording has a little too much bass.
Heresy! The single version is perfect. Although I could’ve gone for a second verse. 
I’m adding this song to the list of songs to play along with when I practice, by the way. I never really thought about how good it was until now.
I’m listening to the original song right now, and the bass line is way better. Rhythmically it mimics the vocals (the “some-times-late-when-things-are-real” rhythm) which of course fits much better in the song than the “dut-rest-dut-dut” bossa pattern that the guy in the video was playing.
Ventura Highway also has a great bassline, too. I like it when the bass line comes into the song late with a run up to the high notes (Friend Of The Devil by the Dead also does it.)
Yeah, he’s playing a different rhythm than the original bass line.
Another video (labeled “Ventura Highway (live 1975)”) looks like the same people on the same stage and gives credit to Calvin Samuels. The listing for Calvin Samuels at Allmusic.com is for a member of Manassas. (Or is it supposed to be Stephen Stills’ Manassas?) I couldn’t say for sure, but pictures (via Google) look like it could be the same guy.
If it is the same guy, he did a good job on the Manassas (studio) album. But the part he’s playing on this video is just not as interesting as the original. At least he’s playing in the same key as everyone else.
It sounds to me like what one of the YouTube commenters said: the guy was just filling in and probably hadn’t had time to learn it correctly. As a bassist myself, I can hear what the guy is doing - he’s locking in with the kick drum, i.e. pretty much playing the same rhythm as the kick drum. That’s the standard fallback for bass players when we’re “faking” a song. While it might not be the “correct” bass part, it provides an “acceptable” bass part, and in a performance situation it’s better than no bass part at all
I interviewed America at my college back in the 80s. America had a roadie/tech named “Doc” IIRC, and he came out on stage to play about once a night. Perhaps it’s him.