One thing I thought I'd mention. Snakes don't eat their prey live. They kill it first, then eat it whole. If you want to see some thing eat their prey live get a gecko, frog, toad or another such animal that eats live prey (usually bugs of some sort). Putting a rodent through the stress of being crushed to death isn't the most humane thing to do either. We raise rodents for our snake food but we kill them first (usually we use dry ice in warm water, the rodents pass out in under 10 seconds and in general it's a pretty painless way to go). Seeing as the snake eats dead food there's really no reason to feed it live anyways, there's no thrill in watching a snake crush a rodent to death it just sits there and squeezes, and odds are your snake would do it with a dead prey item too (most of ours do). So why put the snake at risk and have either the preditor or prey suffer a slow death? I can't think of a good reason, can you?
Oh ya, as a rule, boids tend to just sit there while colubrids are a little more active.