Something else to add here is that it will depend on the type of MVP you are going for:
Technology MVP
All of the above. Doesn't matter how long you have been working with Sitecore or what your skill level is, a Technology MVP is all about contributing to the community.
Digital Strategist MVP
Again this is about contributions, but sometimes with a strategy role, the work you do cannot be shared with the community due to NDA with clients etc... So with this type of MVP, you can detail in the nomination what you have done to help clients realize their digital strategy using Sitecore - but community involvement is still important if you can
Commerce MVP
Similar to Technology MVP but with a slant toward Commerce and also those that are using Sitecore Experience Commerce to deliver client solutions. Although, I would guess that those 2 things go together anyway :)
Ambassador MVP
This is less about community contributions and more about people who help provide Sitecore with feedback on the product and participate in panels setup by Sitecore for this purpose. They should still participate in community events, but will probably be doing more behind the scenes work to help Sitecore than other MVP types.
tl/dr;
Community, Community, Community - and the important thing to note here is that it is contributing to the community, not just watching community. Being on Slack or SSE isn't a contribution - actively participating, answering/asking questions, presenting, writing your own blog posts - that is the key and what should go on the form. Adding that you watched a video on Sitecore on YouTube! probably not!