I watched the video and it pains me to say that there's a lot of misinformation in it.

Here three examples:

Claim: "Microsoft is no longer investing in Skype for Business".
Fact: Partly true, because Microsoft are heavily investing in Microsoft Teams

Claim: "Multiple tenants are required for external communications"
Fact: Simply not true

Claim: "With Microsoft you need to invest in an E5 license for messaging, meeting and calling"
Fact: Not true. Messaging, meeting are part of O365 E3 and PSTN is enabled through an add-on call Office 365 Phone System