I think this video is a true gem of both the audience of the time to appreciate Lupin III and how voice acting was perceived at the time (at least among kids!) - something very mysterious!. 
(I doubt that is true today with how much more visual in Japanese society seiyuu has become since Lupin III, it’s a profession that has seen immense changes, while retaining many of the same things!
And the matching voice with character thing is hard as a kid! It just is. I doubt I’d do much better.
Basically, what I think here is that these voice actors are actually a bit reproducing “voice expectations” for their time (70s? 80s? at this point) and that means there and “affect” to their speaking habits, as there is today to seiyuu’s “acting habits”. Or that’s my thoughts about is.
I might be wrong for sure, but there is a generation of seiyuu with speaking habits/ patterns/ ?? that are clearly a sign of their time, and I always wondered what that was about?
I love so many of them, but also, dislike some of them for their “theatricality” - and a connection I sense ( I don’t know anything really) is that they have theatrical experience on theatrical stages before going into voice acting.
I do think that was a thing in the past for some actors, and I’ve already posted about the sense of condecention you got for going into voice acting, compared to just a (“normal job + waiting for the next role in “real” acting”), read more about this in the Advents thread, but is still bothers me that both Yamadera-san and Akio-san were talking about this as normal to see stage acting in one light and seiyuu work as low-level work you don’t bother with! - that’s just sad! : (
and Tomoaki Maeno (rising star seiyuu! 
) make tin sake cups together!
(with pro help of course as in the previous vid, but still, they’ve got some nice ideas here!)
