In the current release of the 0.16.0 beta you can not create worlds of the old type because its not in the world generation options, you also can not turn already existing worlds into infinite and when you launch up a mcpe old type world from 0.8.0 the game crashes
as for screen shots I don't currently have the beta installed
MCPE-17514
Old World Types And 0.16.0/0.15.90.7/0.15.90.8
Resolved
Cannot Reproduce
0
(Unassigned)
Unconfirmed
Tablet - Android - Amazon Kindle Fire
FireOS 5.3.1.0
0.15.90.8
Retrieved
You're able to create old worlds in 0.15.90.8, and you're able to convert them into infinite worlds. The crash you're mentioning would be a different bug, so please make a new report for that issue using the Bug Report Guidelines Here.