Is there any point in using the seamless and or sandbox attribute for YouTube iframes?

Question

Update: This question is no longer valid. See comment below.

1. YouTube embedding is done using iframes nowadays.
2. HTML5 introduces the seamless attribute

Answer 1

No, fullscreen does not seem to work with both attributes enabled, if you are in the HTML5 beta check an example here: http://bcmoney-mobiletv.com/view/2133/monty-python-tax-sketch/

However, when I leave the HTML5 beta program it plays back in the standard YouTube Flash player, which ignores those iFrame attributes completely.

So, it really depends what your goals are. If you want added security and an experience that feels more like an in-page web video that is controlled by your page, go ahead and use those attributes, however, if you want to give the user a full range of controls and options, leave off sandbox and/or seamless.