Just two weird things I noticed in the spiders tactical AI behavior in regards to web.  Not specific to .912, though I have seen in there already.

So a spider and I are fighting one on one.  Why on earth does it waste a turn where it can reach me and get first attack to throw a web.  It's just the one spider and my one unit.  They have to close to melee and web doesn't have any affect except immobilization.  

When I have more than one unit in the battle, they always web my strongest unit, even if its a caster despite the fact that I have a hard hitting melee guy in the battle as well.  Webbing my caster does nothing if I can flame dart all day and then still chase the spider down with my melee guy.

Also, if I group a unit next to a webbed unit, the spider will position itself to attack the webbed unit, rather than positioning itself to take advantage of the fact that one unit is immobilized.