Since the Mi Box can't be powered by the USB port in my TV I am now down to two choices, the google Chromecast, and the Roku Streaming Stick plus, my question is can I play local content in my phone on either of those devices? For example: I have a movie in my phone, can I play it in Chromcast? The same goes with Roku? I'm eyeing chromecast cause it's more affordable than Roku, but Roku supports 4k without the need of a power adapter, your inputs are much appreciated.
Just an FYI, USB power isn't recommended for Chromecast either:
https://support.google.com/chromecast/answer/3212934?hl=en
The first gen will generally work, as long as a properly powered port (some are not - some don't provide enough power, and sometimes the power is flakey).
Both 2nd gen models recommend using wall power, and the Ultra specifically says that it won't work from a USB port on the TV.
I wouldn't assume the Roku Streaming Stick+ will work over your TV's USB. Many don't meet the requirements and will not boot past a screen telling to plug into wall power.
Find a way to plug in so you don't have to settle.
Your USB port must supply one full amp to power either device. A lot of them are 500ma which will not provide enough power, so double check that first.
The device will be shut down when the TV is off, which means it will take some time to boot up when you want to watch TV and the Chromecast will be unable to automatically turn on your TV when you cast something to it. They also won't install software updates out-of-sight.
Both devices come with an AC adapter in the box, so you don't need anything extra if you don't want to use the USB port.
Aside from that, Rokus are nice for having a regular remote and menu system, but they don't do well for casting files from your phone or the phone's screen. Chromecasts are better for that (if your phone supports it) but everything has to be controlled from a phone and the Amazon Prime experience sucks, if that matters to you.
What I don't understand is: Your TV is hooked up to a power socket. Why do you not use a power strip on that Socket and then connect both devices?
If you are still going with the chromecast: BubbleUpnp, VLC and Local Cast all do what you wish for.
You can cast videos that are saved locally on your phone (assuming it is Android) to a Chromecast using an app like Local Cast.
Make sure your router is compatible with the /r/Chromecast or you will have a lot of pain
Bubble upnp will let you cast local media on your phone to Chromecast.
Best option is a cheap computer (old laptop maybe) and a k400 keyboard.
There's a new box https://androidtvbox.eu/himedia-s1-is-a-new-tv-dongle-with-android-tv-8-0/
It is powered from USB, but it's not on sale yet. I believe it will go on sale in mid October.
Sounds like your power problem would be easier to work around is there a particular reason you need to plug it into the USB on the TV?