I'd be cautious about installing any apps from the pgyer.com website. Some users in the WhatsApp beta thread who downloaded from that site suspect that the app may contain the WireLurker malware as it uses an unknown enterprise provisioning profile. Not sure if this is true about the MovieBox app downloaded from there, but exercise caution peeps.
I agree this is risky, potentially more risky that just jailbreaking and using Cydia since the sources are known. I have uninstalled and removed provisioning profiles using Xcode.