You can try one of these;
There is a app for Ning...PollDaddy but I am not sure if there is code to copy and paste into a forum.
It's what I read when researching this. any code that's not put in using included features like the video embed code box will be removed.
That is not unusual in forums.
What is unusual is that there isn't a poll feature included.
Any plans for a forum poll feature?