I like low key videos like this, but it's unfortunate that he missed the opportunity to explain how and why table tearout occurs. In so doing, he leaves his viewers at risk of badly damaging the T-Slots on their machine tables.
Anyone not already familiar with the overall issues of compression and tension loading of cast iron might benefit from reading this thread and the ones it links to.
Cuts for the angle were very light since it was only held by one clamp. One tight clamp but still only one.
I "THINK" that you might have a problem with your clamping arrangements. You probably won't find this info in a book or a video. You learn about this by personal experience (to be avoided) or by hearing about the mistakes of others.
1. Never allow the bolt to extend below the T-Nut.
2. Always try to achieve compression (columnar) loading of the T-slot clamping system. Tensile loading should be avoided.
3. Avoid over-torqueing a T-Nut and bolt.
Here is a photo of the Mill...