First, I'll apologise for the late reply. My excuse being I don't frequent the forum as much as I used to and only recently noticed your post, and with any luck you may return to it.
First, let me sympathise with your recent disaster and say quite plainly that in my humble opinion the blame for the loss of your valuable Whatsapp images, video and audio, should be placed quite firmly on the desk of whoever decided to have CCleaner for Android pick up these valuable files as something to be considered for deletion. Of course, just my opinion.
When I first installed this latest version I had to look hard to work out what exactly CCleaner was flagging from Whatsapp. Are these items unnecessary thumbnails, or some sort of hidden cache? Because lets face it, CCleaner as a tool has always been used, from the time of it's inception, to remove crap from ones computer, and now from ones smartphone or tablet.
For that reason, I can understand why you believed it to be the safe program it's always been, and went ahead and deleted what you no doubt believed to be unnecessary files. In other words "crap" to be removed by Crap Cleaner. And I'll wager you're not the only one to trust CCleaner to do what it's always done.
What stopped me was simply the size of the files being flagged. Hundreds of mb just didn't ring true. A less experienced user may not have stopped to ponder what's going on here.
However, my strong feelings about this don't help you get your files back.
My first question is do you have Google Photos and/or Google Drive activated to back up your photos and videos? That's the obvious solution, and I'll leave it at that and wait see if you return to your topic.
I will add, that I've removed this version of CCleaner from my phone and sideways installed an older version. For whatever reason, the developers have removed almost all settings from this latest version, and there isn't even an option to exclude things like your Whatsapp files. They aren't checked by default, and they shouldn't even be flagged, but they appear every time you carry out a scan.
I find this sad, because this latest version looks extremely professional and polished, but the dramatic changes to it's functionality are heading down a road I'm not prepared to take.