About a week or less, I think.
Let me detail it a bit more, just so no one thinks I'm trying to stir **** up for nothing. Back at E3, Smash was at the top of my "new content" tab on youtube, thanks to the two newcomer videos, along with the Nintendo Channel. Then it disappeared from the tab as other channels I follow uploaded new content afterwards, while Nintendo's stayed up at the top of the list because of all the trailers they released aside from Smash.
Today, though, I check my subscription list and the Smash channel is back at the top, right next to Nintendo's. Furthermore, the same thing that happening pre-E3 is happening on my phone (if I click the Smash channel, the blue dot goes away, but when I reset the Youtube App, it reappears).
I had my suspicions Hero would be released either by the end of this month or the beginning of July, so this kinda fits the bill. I'm just curious if other people are getting this.