Yes, it will auto go to landscape. That is the only display that will work with this app. You still can exit and rotate the app by first disabling your auto-rotate on your phone and then open the STube app. It will still auto-rotate to landscape mode but when you exit it will auto-rotate back to portrait mode. Then you can/should re-enable the auto-rotate function on your phone.
To get to the menu side card all you have to do is swipe from the right side of your screen and your task bar should appear. Then just press the back button once and the menu will appear on the left side.
To exit the app just double press the back button and it will take you back to your homepage of your phone.
To easily navigate the rows just press any video pic on the bottom row and the rows will advance one at time. you can scroll somewhat, but it will only scroll 1-2 rows and then start over.
To move he row right or left just press on the vid pic on either the right side or left side depending on which direction you wish to search.
I don’t believe you can cast with this app on any device, but I know I couldn’t on my phone. I have not tried to connect via Bluetooth to my portable speakers. So I am not sure about that.
Just type Troypoint Toolbox into your Chrome browser and it will take you to the Toolbox. Then scroll down until you see the app and download and install.
Movies will be a hit or miss. The movies that did play booted quickly and played without issue. Some movies would not boot and stated the video format is not supported. TV shows are the same way. Some play some don’t. You will have better luck by do a search for Free Movies and Free TV shows. I got several to play doing that search.
So open your chrome browser and type in Troypoint Toolbox. Then scroll down to the SmartTubeNext app and download and install.
Good luck…now it’s my nap time. lol 
Just remember this app is NOT optimized for phone use. However, it will work. You will have to do a bit of learning (experimenting) to figure out how to maneuver around on the app.
Btw, Miki gave you the address to use in Downloader. So you can type troypoint. com/tb (lose the space after the dot) in the browser and then copy and paste it in your Downloader favorites for easy access or you can save the web address to your favorites in your Chrome browser.
Oh, and if you want to, you can place a shortcut on one of your phone’s screens.