I didn't watch the whole video but I read the study. There is a lot of excitement about this study, but the details in it matter. It was randomized - but when you look at the two groups (treatment vs. control), they had some key differences. The control group (who didn't receive Vitamin D) had more men (69% vs 54%), more people with hypertension (57% vs 24%) and diabetes (19% vs 6%). These are all areas that increase the risk of severe disease. So the groups were not the same. If you just compare the numbers of those who went into the ICU vs. not, then the results look amazing. But once you correct for hypertension and diabetes, it was not so impressive - it was not statistically significant in the study. This does not mean that I think Vitamin D has no effect. There is some evidence for Vitamin D in respiratory illnesses. But the effect is not as dramatic as some of the headlines for this study would imply.

To add to your question, here is the latest study that was linked here last week...

https://www.sciencedirect.com/science/article/pii/S096007602...

OP's article does not address Vitamin D's effects on COVID.

It indirectly implies that it may be efficacious though as it mentions respiratory infections as one place where meta-analysis has shown benefits.