Roberts Grove (located in Placencia, Belize) recently posted a few short videos on their YouTube Channel featuring some footage of whale sharks at Gladden Spit. While there’s nothing groundbreaking in these videos, I never get tired of seeing footage of whale sharks.
Having been out to Gladden Spit multiple times during "whale shark season", I highly recommend it. There is plenty of great reef diving in the area, as well. While the whale sharks can be hit or miss even around the full moons of the spring months, dolphins and bull sharks can be commonly seen at Gladden Spit, as well. So, even if you miss the whale sharks, you likely won’t leave disappointed.