I sold my iPhone 4 and before I sold it I erased everything and I saw a video that?

I just saw a video saying that who ever I sold the phone too can easily get my photos and everything back! Is that true? I was at school and my brother came and took my phone because he found someone that wants it I gave it to him and he said he will format it… I'm really scared I don't want my photos to go everywhere! They also said in the video that this happened to a girl! My brother sold it to some girl I'm really worried is it true that they can get the photos back?

More specific please

It is better to erase everything if you want to sell your iPhone to other or don't need it anymore. I'm not scaring you, your information on iPhone, like photos, videos… Can be recovered by some iPhone recovery tool. Generally, the tool costs $50. If somebody really want to steal your private information, they can do it.

False.
An iPhone does not have a hard drive. It just has memory. If it were possible to recover data, an average person can't do it. You'd have to be one extremely tech literate person. You can't just hook up a formatted iPhone to a computer and recover files.
Don't worry.

I doubt she'll even try to get them back. Why would she care what pictures you had

As long as you did the erase content and settings option then you will be fine.

No, as long as you went to your computer with it plugged in and hit restore to factory settings it should be good.

Its okay