I was able to reproduce the behavior you observe on Galaxy S3 with 4.1.2 (the closest we have to your Galaxy S2) and after some comparison with my phone on which it worked, I identified the problem. Mine, where it was working had Settings > Developer options > Force GPU rendering checked. Once I checked that on the Galaxy S3, it worked as well, so I suppose it would work on your end as well. Clearly this is not a clean solution as telling all your users to enable a setting which is not even visible out of the box is far from optimal.
A quick google search about "android video iframe" shows numerous complaints that it does not work, so our suggestion would be to simply use HTML 5 video tag which in Android v.4.x.x is supported fairly good. You would need to enable hardware acceleration from the Icenium project properties for this purpose.
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