Are videos automatically 1080p

If it's through the app, the resolution is always set to the highest possible setting for the video itself (so if the highest resolution is only 720p, it will be set to that). If you're on youtube.com via the Internet Explorer app, then you'll have to set
it just like when you're using IE on the PC.

Some games don't upscale to 1080p. Check the back of the box to see. I know sometimes PS3 and 360 games only come out at 720p, but other times it automatically goes to 1080p.

-

I think it depends on the game. If your settings on your 360 are set to 1080p and your tv definitely supports 1080p and you have used multiple hdmi cables, then it has to be the game.

-

Also, check here.
Improve video quality of xbox 360

Ok and if i have set 1080p in settings xbox automatically downscale 4k to 1080p?

Can you try a different picture setting. Like changing the size of the picture to 1080i or 1080p (if possible). Also try setting the xbox to see if it can automatically detect your tv's picture settings. Also have a look here

support.xbox.com/.../audio-video it may help

[quote user="REK 1"]but it was not really designed to run at 1080p,[/quote]What, the scaler? Scaling's done by dedicated resources in the GPU. Because it didn't ship with the feature doesn't mean it wasn't considered during design.

nothing on xbox
live video or games run at 1080P

Untrue. There are many 1080p videos on many of the 360's video services. I own Archer on Zune/XBOX Video. Those episodes are 1080p on the 360. Ever try to read the label on a bottle of Formula K at 720p and then at 1080p?
Big difference..

720P is most and xbox upscales it but not native,

The 360 can output a 1080p signal. What the source material was is of little consequence.

like if u put 1080P video in xbox, it will downscale it to run through the cpu/gpu
for more speed then it will upscale it in the video output

This is gibberish.