Search & Play a video and Categories & Play a video still work.
I did notice I have to login again to see my subscriptions though. I haven't tried if that works.
There are still some other apps in the store such as EvercastorStreamy (both from the same developer) which have ads (which you can buy away for 3.49 euro I hope it one time pay) and have Slide Over/Split View and background audio play. To be honest I didn't buy the pro version of those because ProTube still works ok for what I use it for. I did notice however that the mentioned two apps don't seem to be appearing in the UK or US App Store but in NL.
Not sure though if those apps support iPhone X though? I don't own an X.