Obama is trying to stop this video from being aired.
Here is Front Sight’s round up of Obama’s vote. I’m not seeing anything on Obama wanting to tax guns.
Here’s Earned Media’s round up and again nothing on taxes.
According to the Washington Post, not exactly a bastion of anti-Obama’ism, said that the taxes on guns was based on Obama’s support of a 500% increase on the types of weapons that have been used in crimes. (Which is just about everything.)
So, his support of a gun tax isn’t new. But he hasn’t said he has changed his position either.
I would say that the speaker’s being disingenuous to say “now I learn,” but he might just be learning.