[Draft post] (Comment to get Google doc with statistics)
I measured approximately 14 MByte/minute consumed watching a 2-D SD Periscope video (HD is available for broadcasters with API. This is tractable even with prepaid cellular plans, depending on how much you stream.
The columns of this table are for streaming a particular stream vertically and horizontally, then another stream horizontally only. The data usage readings were taken once per minute on an Android device.
|Horiz stream #1||vertical stream #1||Horiz stream #2|