I do believe that implied consent is perfectly reasonable in a long term adult relationship, in fact I think that most relationships work with implicit consent.
I agree that most relationships involve a lot of implied consent but just as often include explicit consent. Either way, you learn pretty quickly if there was implied consent or not (you try to initiate something you think is implied and you find out rather explicitly that it is not) and either way explicit consent is a lot better.
Here's how my conversation about it went:
Her: "ok babe, I'm going to sleep"
Me: "I'm gonna work for a bit but I may come in to bother you in a later"
Her: "go for it, I don't mind being woken up like that"
I probably wouldn't just have winged it that early in the relationship and dove right in so to speak, because I am thoughtful (or try to be) and understand that some people do not wish to have sex initiated while they are sleeping.
This kind of video helps people think about those kinds of things, that just because we've had sex a few times doesn't mean she wants surprise night sex.
This means that consent is assumed and it is perfectly safe for a person in a long term relationship to start sexual activity unless and until the other person says 'no'.
Not all communication is explicit, to me these cases have communicated their consent (which is what you mean by "implied" consent). Acts and behavior over long time are tantamount to communication and communicating consent.
The problem comes in the real life cases where things happen and people make mistake, particularly with young people. If you are dealing with emotions, mixed signals and alcohol things happen. You want to tell kids (or some adults) to always be responsible. That isn't always going to happen.
And that is what this video is addressing, the many young folks who think with their pants and don't even consider consent, and who see a passed out person as fair game.
Often there are real, serious consequences for both parties. In these cases getting the definitions and policy right is very important (and in my opinion often quite complex).
Consequences and policy may be complex, consent really isn't. This video doesn't say a word about consequences and policies, it's just explaining the simple concept of consent and largely directed at young people who have not given this much thought.