HI,
The atm dialer config looks fine.
IF you are able to get to the internet the connections is good.
The issue you have is specific to the video calls not reaching the router we will need to check the nat traslation. show ip nat trasl will show you if we see that video ip address is getting to the router. We can enable debugs ip nat and take a look at issue.
If you are not a router guy, i would recommend that you open a support case with the cisco TAC and they will be able to walk you through isolateing the issue.
Debugging can be chatty if you have a lot of traffic and i would not recommend enabling it if you are not sure of it.
You can also do QOS on the router to give priority to the video traffic so that you get good quality.
hope it helps
Ray