Just a heads up, this might be obvious to some (most?) but it took me a long time to figure out:
If you have an ampersand in a URL in a textfield, the flash version will work but it will fail on the HTML5 version.
Replace the & with "

" in the URL and and the URL's should work.
Also convert the angle brackets "<>" to square brackets "[ ]" in your data field.
Hope that helps someone.
Roger