I just noticed that it is now possible to participate in Beta testing directly from within the Play Store app. These apps will then show up in a 3rd "beta" tab.
But it seems these feature must be enabled by the developer. Do you consider to do so?
(Here is explained how to set up open beta testing)
"With Open Beta Testing, instead of adding testers to Google Groups or Google+ Communities, you can add testers by sharing a specific link with them. Your current testers will still be part of your beta program."
But where do I find this 3rd tab? Something I have to activate/enable first?
Edit: "Latest Play Store 6.7 Enables The Beta Testing Features For Some Users" http://www.androidpolice.com/2016/06/29/latest-play-store-6-7-12-enables-the-beta-testing-features-for-some-users-apk-download/
Seems like I'm not the a chosen one
The third tab appears as soon as you as you participate in an open beta.
See the screenshots.



So I just switched to Open Beta Testing. Not sure what happens to users that are already testers. If anyone has any issues, the link is: https://play.google.com/apps/testing/de.danoeh.antennapod
Oh, so I'm one of the entitled ones. Your current beta tester will stay in the beta program and will automatically be added to the open beta.
I'm an alpha tester; I guess nothing changes for this group.
Updated the relevant wiki page.
I'm a beta tester and got seamlessly transfered to the open beta programming. Here some screenshots.


BTW. Do you need some screenshots for the wiki?
@stonerl Thanks. I've created the screenshot below, which I wanted to publish. Or do you think including anything else would improve understanding?

No, I think your screenshot is sufficient.