When they bought Youtube, Youtube did not earn any money and it was spending probably much more money than Waze.
Google had their Google Video. The difference is that Google video was crap.
For me what is better in Google Maps is:
Livemap of course
POI
Search
Reliability (it never give me a timeout when doing a search or a route)
Speed (they find routes quickly)
Map data
What is better in Waze:
All social features (sharing danger, accidents)
The map that is updated everyday
Traffic
So waze has a lot to get from Google, and Google has also many features from waze that are interesting for them.
They can learn from our editing community (because MapMaker is not exactly friendly, you change one thing and it takes one month of talk to know if it is accepted or not) and many other things.
And Google Maps would be a great basemap for many countries where there is no basemap.