Not a fan of Floyd or 50 attitude wise but there's 2 things that need to be taken into account.
1. Floyd did read the words, just not as fast or at steady pace. Not everyone reads at the same pace and some people have to start over to catch themselves when they stumble over words.
2. Not everyone is conformable reading in public. Some read worse in public than they do when alone. Back in school I used to hate reading in public for a while because I had/have a stutter but it got better over time. I loved reading stories and books to myself as well as writing. Loved reading by myself(stories/books/comics) in school in front of people was another thing all together, at least in my mind it was.
I think its messed up because I don't think Floyd knew that the sound clip of him messing up would get out to the public. However on the flip side its hard to feel sorry for dude because he does talk so much trash all the time. Maybe this will humble him a little?