Referring to Randi's explanation for the SRI "die-in-a-box" experiment in 1972:
"In his book "exposing" Geller, Randi explained the first by suggesting that, in front of investigators Puthoff and Targ, Geller picked up the metal box, opened it slightly, peeped inside without them noticing and replaced the box. he repeated this process eight times, but is so skilled at misdirection that the investigators did not notice, and the actions were not recorded on the videotape monitor."
Remarks
The simple reason that no such sleight-of-hand was recorded on film is that the only film taken was of the very last of the ten attempts, on which Uri chose to pass as he wasn't confident. The fact that only one of the ten trials was filmed was only revealed in 1982