Added Video Embed Code Sends Rw6 into Shock and Freezes Mac!

Hey everyone,
Today while working on a website I added the code for a video advertisement to a page using the html stack, which I have done on numerous occasions. However, today, when I chose preview, Rapid Weaver went into shock. RW Froze and then my Mac froze as well.

I did apply Einstein’s theory of insanity and tried it again expecting different results but it happened again.

I put the embed code in an online html editor and it works fine.

I am using RW 6.3.8 The YourHead Stacks are up to date and I have not added any new stacks.

Thanks in advance,