Put it this way. That video, and equally a visual inspection of the videoed experiment, provides zero evidence for high energy production during the boil-off period.
Those claiming that although it is not clear, we must believe F's interpretation because he was expert and could judge better than us are on a sticky wicket, for many reasons.
OTOH, if there is other good evidence of very large excess enthalpy during boil-off those foamy test-tube pics are not needed, and for the same reason it is difficult to be sure that the white stuff is low D2O density foam.
Perhaps a more pertinent question is why was F are offering such poor and ambiguous evidence of high power production? The obvious reason: because he did not have more convincing evidence.
If the process is self sustaining, an Olympic swimming pool could be boiled off, no?
Connect the equipment to marine batteries to get needed voltage, then the input energy
Quantity is known, the output energy would be whatever amount of water is bolied off.
Pretty simple really and absolutely identifies
an energy producing process.