This accessory may not be supported?

I have an iPhone 5c and I've been getting a notification coming up saying that "this accessory may not be supported" every time I try and carte my phone. At first, I thought it was my charging cable (which is Apple manufactured) and then I used my brother's, which was in perfect condition, and the notification still kept popping up. I tried all of the possible ways to fix it (resetting your phone, cleaning out lint from charger opening, etc.) and nothing seems to work! My phone isn't able to charge and I'm worried it's a problem with my phone and not the charging cables. What should I do?

IPhone camera roll won't play videos?

Someone please help me.
I have an iPhone 5S and whilst scrolling through my camera roll recently, I discovered that some of the videos will not play - but instead come up with a 'buffering wheel'? There's no bar at the top which shows the content of the video either, but the thumbnail still remains. I'm so upset about this if it means I've lost the videos, as they are extremely important moments!

P.S the videos in question are all ones SAVED to my camera roll from snapchat, rather than being taken on the camera mode.