Lets wait for things to become clearer. People circulate videos from any state, sometimes from any country and try to pass it off as something else. Even the article you posted says 'alleged attacks'. People can leave based on rumours. In the past people from North East left in hordes from Bangalore after similar rumors. Come to Bangalore and see how many people from North East work here. Restaurants, salons, they are full of them. Stop believing some shit that has been posted on a foreign forum that will lap up news of trouble inside their enemy country .
Regarding your point about Hindi imposition, I am not saying it has been done, but some BJP leaders do keep making statements to that effect, which itself is unnecessary. It rekindles memories of the time when it was actually tried. So don't talk as if there is no ungli being done.