I've been wondering about those "shares to be paid" values myself, so I had a look at the code behind it.

The values you're seeing are the sums of the "share values" for each valid share you've found. This value is calculated as f(share difficulty, net difficulty,block value). I'm not sure this is an actual exact value, as it was my understanding that each time a block is found on a p2pool network each miner is paid relative to the number of valid shares he's submitted during the N last rounds, and proportional to the total number of valid shares submitted by all miners. If a round is long, the share value should decrease and vice versa.

Simplified, it would be something like:

     VTC_reward=(personal_shares_Nrounds/total_shares_Nrounds)*block_reward

I'm not sure the actual value of a share can be known before a block is found, which would mean that those values we're seeing in the stats could be exaggerated or not depending on the pool's luck. Maybe it's an average, expected value being calculated?

I'm speculating here though as I'm only just starting to learn about these things, if someone with more detailed knowledge could chime in that'd be great!