Hi Giancarlo,
It looks like you're using Brigthcove, is that correct? Are you also using their ad plugin? If so I don't think you have direct access to the IMA SDK - you'll need to ask them how they've exposed this settings.
In HTML5, "this" refers to whatever the current object is, so what "this" is will depend on your implementation.
Thanks,
Shawn Busolits
IMA SDK Team