How to get back deleted photos on iPhone?

My school went out to ski/tube today (I live in Canada) and i took a very funny video of a guy singing, but my teacher caught me and told me to delete it. Right after I did, he said it was just a joke

I want to get it back, but I don't have any recoveries or any syncs with that video; I just filmed him and hours later I deleted it

I have a jailbroken phone, but I can't pay for any apps so please help me with a way that is free!

If you want get photos (camera roll, photo library) back after deleting them from iphone 4, you can use Dr. Fone (iPhone 4) to directly scan and recover lost photos from your iPhone 4. This video shows you how to recover photos within three steps

I once deleted all the photos and videos off of my phone. I plugged it in my laptop using the USB compatible charger then went into My Documents on my laptop. From there I could see the devices plugged into the computer and my phone was one of them. I clicked on my phone, found the folder that my photos were stored in and they were all still there.
I'm not sure if this will help or if I just got lucky but I hope it works for you.