I was a bit suprised by this stunt, and the record of 8+ minutes and did a bit of research on it.
You see I was present for the record setting by Robert Foster, in San Rafael. It was a long time ago and occured at the Bermuda Palms motel, San Rafael CA (where I grew up). It was in the late 50s or early 60s it think. I was a little tike at the time and I don't remember the year (I would guess '59 to '64), but it occured durring a local boat show.
He hyperventelated O2 and lay on a lounge chair at the bottom of the pool. From well before the record attempt until well after he was attended. I witnesses the start and the end, but was too bored to watch the whole time. Many others were present.
It was announced in advance and was well covered by press (at least 15 reporters present, plus doctors, etc) at the time. I though it was something like a bit more than 10 minutes(though lately I have heard closer to 13 min), well past what Blaine is attempting. It was documented in the local paper (the Independent Journal), the San Francisco papers (at least the Call-Bulletin and the Examiner) and also made the national press.
It was not 'certified' by AIDA because it was about 30 years before they were created in France. When they started the ignored all previous records, no matter how well documented.