CGI Clone Wars rebooted alot of stuff about Grevious. One, instead of being forced to become a cyborg due to a shuttle crash in the old Clone Wars EU, he
willingly chooses to become one to become a better fighter, particularly against Jedi. As to the coughing thing....it's never really given any explanation in the show. It's just assumed the coughing is a side-effect of Grevious's remaining organics not taking well to his cyborg implants. In other words, it's always been there.
Don't know what video you are referring to, but this is essentially correct. The "hierarchy" of canon the old EU had is gone. Disney rebooted it so only the movies and CGI Clone Wars were canon. All the old EU material is now non-canon (under the "Legends" banner) and has ceased publication. However, moving forward, all new Disney Star Wars books, comics, video games, etc will be canon and on the
same level as the movies, as opposed to a few steps down the ladder in the old EU.
There's been a few Disney Star Wars novels so far that have been hit or miss depending on who you ask. Marvel also has a few Star Wars titles running that have been given positive reception so far. Their
Darth Vader line in particular is interesting because it has Darth Vader engaging in a sorta House of Cards-ish situation with the Emperor because the Emperor had stripped Vader of nearly all his rank because of his failure to stop the first Death Star from being destroyed.
However, like all comics books, it does have some...
questionable dialogue.