Hi,
It appears that DART RichMedia Ads, (which do work with the original writeCapture) are not working with writeCapture2.
I have reproduced everything on jsFiddle. The non-working RichMedia ad embeds scripts, and inside those scripts are also document.write calls which embed scripts, and so on and so forth. I think this might be what is causing the issue. Depending on what you guys think, I think this might be worthy of opening an issue in the tracker? I will actively try to solve this issue in the next few days, and for now just use the old writeCapture.
Here is an example of a non-working ad:
Here is an example of a working ad:
NOTE: Because they are in jsFiddle the errors in non-working example relating to "DARTIframe.html" appear because they aren't on a doubleclick site (I'm pretty sure these errors do not effect the display of the ad, they don't appear locally). Same thing with the "Unsafe JavaScript attempt to access frame with URL" errors in the working example.