See this jsbin for a working writeCapture2 example:
http://jsbin.com/agekom/3
The reason for the jsbin/jsfiddle is to give us a WORKING example to
play with. Neither of your fiddles work, you've just pasted your
source code in without actually making it run and reproducing the
issue. You have to meet us half way if you want help.
For the original writeCapture, make sure you've turned on the
writeOnGetElementById option. It looks like your ad script wants to
create and submit a form in safari, which wont work without that
option.