Monetize THIS brand

Hey guys,

One of my clients teaches how to train animals on youtube (mostly dogs).

We are having issues monetizing his brand and feel like we are missing out potential dollars.

• He offers free pet training lessons on youtube that get a ton of traffic
  
• He offers courses on his site that teach viewers more in depth taining for pets that sell ok..

But...

• He gets a TON of requests for custom lessons like: "how can I train my dog to bark certain words?", "how can I train my dog to go fetch a certain stuffed animal" etc. He even started taking custom requests...

We have a training request form that allows users to leave requests and at the bottom, talks about the importance of leaving us a donation but we've only had 2 or 3 20$ donations, nothing substantial.

We get requests DAILY and there is a total demand but the viewers don't seem to want to pay anything?

Also, he's concerned about if we required a 20$ donation for certain requests, he would feel obligated to make videos for the most random requests we get... and no joke, we've received "Teach my dog to catch and eat a bird", "Teach my dog to drive" etc, stuff he simply cannot do, or if he did, would take way more time than to justify the 20$. There is a feeling of obligation if someone leaves a donation and in the notes it says, this is for you to do a lesson to "teach my dog to swim 10 laps in my pool and then use his towel to dry off".

There's gotta be a better way. I really don't want to lose his contract, I need it. Any ideas on how we can monetize the requests

Thanks guys, anything helps, thank you

JT