I’m a Filipino. So, I guess I could help you out here a bit. To answer your questions.. Yes, it is common. And no, it is not confusing at least to us who understands both languages. Its a common thing because our lingua franca permits us to use English during our conversations if it will help us convey our message better. Or if the speaker is not fluent in either language and cannot find the words to express themselves , either in English or Filipino, they tend to borrow words or phrases to fill in those gaps. But its not a thing that’s encouraged especially in academic or formal events because, as you said, it tend to be confusing especially to strictly English speaking listeners.

As to the Brandon Vera interview, their audience are mostly or strictly Filipinos. And I think they wanted to show their audience that he is really a Filipino at heart by speaking the native language. And him being American born and raised, he tend to speak in broken or limited Filipino, so, we hear them compensate by speaking both languages at the same time..

But then, I’m not a Linguist, Filipino/English or Communications major. So..