$ curl -o file-without-ifrange.mp4 -H'Range: bytes=113868800-222029005'  http://localhost/video/file_1920x960.mp4

$ curl -o file-with-ifrange.mp4 -H'Range: bytes=113868800-222029005' -H'If-Range: 345a2dd5c8f22e9ffaf250151ea820df' http://localhost/video/file_1920x960.mp4

$ ls -lh file-without-ifrange.mp4 file-with-ifrange.mp4
-rw-r--r--  1 user  staff   212M Jul  3 16:39 file-with-ifrange.mp4
-rw-r--r--  1 user  staff   103M Jul  3 16:39 file-without-ifrange.mp4

##### Checking Etag from cached file:

$ head -20 /tmp/7/8a/ac18b7bf45855a07bb6b9f05605e78a7
��cY�eVY\�ZY�?(��+ 345a2dd5c8f22e9ffaf250151ea820df
KEY: http://my_backend/video/file_1920x960.mp4
HTTP/1.1 200 OK
Server: nginx
Date: Mon, 03 Jul 2017 19:34:52 GMT
Content-Type: video/mp4
Content-Length: 222029006
Connection: close
Accept-Ranges: bytes
Last-Modified: Fri, 30 Jun 2017 14:52:43 GMT
Etag: 345a2dd5c8f22e9ffaf250151ea820df
X-Timestamp: 1498834362.33768
X-Trans-Id: tx05e1c2ee38284c5885940-00595a9c5c
Cache-Control: public, max-age=604800