Q: all apps require iOS 8. iOS 7 have to die!

my device is iPhone 4, iOS 7.1.2. With this phone, I cannot download YouTube app from the app store because it requires iOS 8. But, couple of weeks ago, I had this app on the same device until I had to go for a factory reset.
Is there any way to download this app to my device? please let me know.
Thanks is advance.