While working on new variants of Responsive Display Ads I realized that now, in addition to the maximum 5 titles, 5 descriptions and 15 images, you can also add up to 5 videos (which are then also visible in the ad previews).
See the following screenshot:
Having good videos available in the advertiser’s You Tube channel, it is certainly worth to test the performance of different text/image/video mixes to be shown to users.
This new automatic optimization functionality will surely change the way we test creatives, since now it is no longer necessary to set many different variations of each ad to know what worked best (both in Display and Search Networks).
11/9 UPDATE: Some other PPC professionals confirmed me that this is an on demand beta available if you are already running GDN campaigns with at least one active responsive display ad in the account.