The cel might not actually be taped to the 
background at all; I find that a lot of the cels 
I bought from private Japanese collectors (as 
opposed to dealers) are bagged beyond all 
recognition--the cel is in at least one bag 
(depending on how many layers it has, there may 
be several bags keeping it unstuck), and the 
background is quite often in another.  The two 
are often taped together so they don't slide 
around.  I'm not sure if that's the case in this 
one, but it definitely seems possible--the tape 
seems like it's stuck to plastic, not to paper.

So I would definitely bid, because I'd really 
regret letting something cool go just because of 
a little tape.