Rattling and Resetting Noise at Muffler, Serious?

[LaiFong]

My 2009 Vibe started making a strange rattling/vibrating sound that goes for a minute or so then a shudder then back to vibrating/rattling but only when in Drive with a foot on the brake. I found where the sound is coming from:

https://m.youtube.com/watch?v=o55hXTxW_ ... e=youtu.be

The engine purrs nicely, but that Muffler is rattling and then sounds almost like resetting. Any advice like what the problem is and how urgent is it? like what might happen if i keep driving it as is?

thanks!


[url]https://m.youtube.com/watch?v=o55hXTxW_ ... e=youtu.be[d/url]