Yes. I opened the Roku remote app first on my iPhone and chose "Devices" in the lower right. I then selected my living room TV. The remote control screen pops up (the one with the 4 arrows and OK in the middle) and there is a gear icon (settings) at the top right. Select that and "Adjust audio delay" appears as a choice at the bottom. Choose that and it will have you point your iPhone at the YouTube video and it samples the delay and corrects it. Make sure you fill your iPhone (or whatever device) screen completely with only the YouTube video as you point to the TV. This fixed the choppies for me and I did this procedure on my iPad as well.
I hope it works for you. I'm wondering if this setting was there all along.
Sorry...meant to reply to you directly.
Did you go through the sync process with or without your earphones connected to the phone?
Earphones in and connected. I tried it on 3 separate TVs and it fixed the problem
That did it! I used the connected earphones and got close enough so that the YouTube video filled my camera phone screen. Thanks.
Glad to help.