Apollo 11 - What did Buzz see outside his window?

Here is an excerpt from a British documentary about Apollo 11. In it Buzz Aldrin says there was something unidentified outside of their craft.

Is Buzz credible? I mean I have never heard anything negative about him. If he is, has what he and the crew of Apollo 11 saw outside of their window ever been explained?

It was a TUFO: A Temporarily Unidentified Floating Object. Link