Pretty good video. I only saw one comment I didn't agree with. He specifically said Skype continues to run in the background.
That isn't true.
iOS is very strict about apps running in background. Essentially iOS always asks an app to do something. If that app doesn't finish handling the request within a few second timeout, iOS will kill the app because its not behaving.
Even Skype, or VOIP applications that look like they run in the background act this way. iOS may periodically ask a VOIP app to do something while in the background, but that app has to complete its work within a few seconds or else. And iOS tries very hard to ask it to do something only when necessary and as infrequently as possible. As an example in the case of a VOIP app, the app can be configured so that iOS monitors a network connection and wakes up the app periodically. But the app can't rely on being woken up more frequently than every 10 minutes. The app can then run for up to 5 seconds in the background else its killed.
The bottom line is that iOS rules with an iron fist and doesn't allow apps to misbehave.
That said, Apple's own iOS apps don't have to follow these rules and can get out of hand if bugs are present. But thats rare and Apple tries hard to fix those bugs.
BTW, this is a major difference between iOS and Android. Android apps are asked to play nice, but if they don't, Android can't really do anything about them, in fact, Android probably doesn't know they're still running and consuming battery and resources. So on Android, it can be very important to close background apps or previously run apps because apps can and do misbehave.