I’m definitely not powering from the TV. I have a Belkin surge protector that has two usb ports and 2.1A total current rating (10 Watt) and i only use one of them so all 2.1A can be supplied to the RPi2. I have no rainbow square in the corner of the screen 
Belkin supply:
http://smile.amazon.com/gp/product/B00ATZJ5YS?psc=1&redirect=true&ref_=oh_aui_detailpage_o03_s00
EDIT -
I just read (on an OSMC forum post) that there is an issue with hot swapping usb on the RPi:
Also from the raspberrypi.org site:
USB causing Pi to crash - Raspberry Pi Forums
At least one person had a similar issue that was fixed with a different power supply. Between these two posts on raspberrypi.org, it seems that it is indeed power related and a practice that is not recommended.
Possible solution:
In the raspberrypi.org forum post at the link provided by @ActionA and as pointed out in ActionA’s post, it is suggested that if you want to hot swap / hot plug, you should use a powered USB hub.