This might help you find the footage

I spoke to a close associate of Mr. Francisco Tatad recently, he's told me that TV stations in our country still have the archival footage of Mr. Tatad's announcement of Proclamation No. 1081. Though he did not specify which stations these are, its possible that the announcement may be in the archives of RPN, IBC 13 and PTV but count IBC 13 and PTV out because they are government controlled and will most likely not give up the footage to you (unless you get it by sheer luck after filing a freedom of information request to them). RPN siguro, may chance pa that you can get the footage from their archives since they are privately owned these days. Just course it through their regional stations if you want any chance of your query being responded to by an actual person and not a system generated email.

Other than that, you can reach out to ex-employees (particularly yung mga in-charge sa production ng segments/shows)/journalists of RPN/IBC 13/PTV as well. They may be able to offer you leads in finding the footage.