Zahyra the video you linked shows that something did indeed happen, but not on the Blizzard side. If it were an issue with the Overwatch server or the Blizzard network then ALL of the players of that match would have been disconnected. In the video 4 players appear to disconnect (or did they intentionally quit?) while 8 remain in the match.
What we can imply from that video is that those 4 players were likely from the same geographical region (maybe even the same country/ISP) and there may have been an internet issue that interrupted their connections to the Overwatch server. Maybe a backbone ISP was targetted by a DDOS and the increased traffic caused their connections to be interrupted, maybe a shared ISP had a router/device issue, we just can’t know for sure.
These things happen on the internet every day. While it may seem to you like an issue specific to Overwatch, these symptoms may just be the result of a different issue affecting connectivity for a specific route through the internet. Different games and services are hosted in different data centers, which means your connections are taking different paths to get there.
This is why we troubleshoot and have you run connection tests in order to rule things out. We also have a dedicated team of network engineers and our network is constantly being monitored. So if an issue does show up in our network or with the game servers themselves, we will gladly let players know. For major impacting issues we usually post an announcement in the Battle.net app and on our BlizzardCS or BlizzardCSEU_EN twitter handles.
If you would like us to assist with troubleshooting disconnections the best thing that you can do is run a WinMTR like I mentioned in my original reply. That will let us see the path specifically to the Overwatch servers, so we can try to figure out where the connection is breaking down.
As for multiple other players disconnecting at the same time, that really comes down to the stability of the internet in your region. You know the server and game network are fine, because there are others in the match that did not get disconnected. We will gladly assist with troubleshooting one-on-one, but sometimes the issues do just end up being a matter of an ISP (or multiple ISPs) having temporary connection problems that affects the game.