That's actually worth a dig for curious reasons. Going to ask some folks I knew that worked at Twitter.

EDIT:They use an in-house system that is custom built. Regularly there is a 5 minute delay for Video Conferencing to Sync up with buffering and encryption:

Although we used this system extensively, there were some drawbacks: it regularly took over 5 minutes to initiate a VC connection. For a 30-minute meeting, this was over 15% of the meeting’s duration! And the quality of videoconferencing was poor because of several factors, including poor egress network bandwidth from our old New York engineering office, packet loss on the network, and the app’s prioritization of video quality over audio quality.

Ultimately they did revert to Google Hangouts:

After a number of pilots, our IT team decided to go with a company-wide deployment of Google Hangouts plus Chrome for Meetings (CfM) boxes in conference rooms.

This removed the 5 min VC Bottleneck:

We’ve easily saved 3-5 minutes per meeting in VC setup time, and people are notably happier.

Thus we are beholden to a timeline of the 5 mins layerover indeed being something that did happen regularly in the past due to VC Startup and that no longer is in effect. A 5 minute lapse is indeed more suspect than not since 2015.

src1: https://blog.twitter.com/engineering/en_us/a/2015/improving-communication-across-distributed-teams src2: http://techcrunch.com/2015/07/09/an-interview-with-alex-roetter-twitters-head-of-engineering/