According to Guinness, "he was monitored by cinema employees during each screening". In other words, Guinness didn't verify this record. Guinness records are more PR than actual records of human achievement, you'll find a surprising number of records either weren't verified by Guinesss or were paid-for records where Guinness came up with an idea unique or specific enough for you or your company to achieve without the bother of actually tracking the record.

This record does seem plausible at least, but you're right to take Guinness with a grain of salt.