How to isolate my yellow colour from everything else in the footage?

OK, so I've managed to highlight a particular colour in my footage for this music video and turn it to yellow.





And now what I want to do isolate the yellow from everything else to use as a matte/alpha. And also to add a glow and motion blur effect that affects just the yellow and nothing else.

Can anybody give me any tips on how to best achieve this please?

Thank you.

Splurj | Creative Multimedia Manchester | Visual Design Manchester | Video ...