Hi,
Just thought I'd share my input, as we have been feeding our veiled with a container for years and have a few experiences to share. 
Using a fairly large container does work best and making sure it is fairly heavy, especially if you plan on setting it down on the floor. Chams will tend to grab onto the sides and if the container is too light, it will tip over.
What also ended up happening with our veiled is that he got lazy with the container feeding. He practically crawls right into the container and barely uses his tongue anymore to catch the food. This also causes the crickets to crawl up his back and escape into the cage. We've also noticed that when he does try to nab a bug from a distance, that he seems to have lost some accuracy, as he often misses.
We are trying to place the bowl further away from his vines so that he is forced to use his tongue, which does help a little, although he eventually still goes right over to his bowl to sit on the edge of it. We have also started letting a few crickets escape so that he can hunt them.
Just some more things to consider, as I have heard of a condition called "lazy tongue" and I think that is what is happening with Frasier our veiled. One really nice thing about container feeding, though, is that you can put some mulched veggies at the bottom of the bowl along with the feeders, this makes the feeders even more nutritious as they can munch while they wait to be munched (hee hee) and also the cham gets a bit of veggies with his feeders, too. 
Hope this helps!
Julie, Justin and Frasier the Veiled. 