Assuming you would like to stream video from one Android phone to another, there are a few things you can do. One option is to use Bluetooth. To do this, make sure that both devices have Bluetooth turned on and then pair the devices. Once they are paired, select the device you want to send the video to and then start playing the video on your first device. The video should then begin playing on the second device.
Another option is to use a streaming app such as AllCast or LocalCast. With these apps installed on both devices, you should be able to open the app on your first device and select the second device as your target. Then simply start playing the video and it should appear on the second screen.