Some balding behind the ears is perfectly normal and can become more obvious as a hamster gets older. So, symmetrical fur los behind ears, when the skin appears normal, is 100% normal.
HOWEVER, as I can see from the video there appears to be a separate patch of fur loss and as you say Ripley is also a bit itchy, I do suspect there is a little something more going on here.
The most likely causes would include an ear infection, ear mites, ringworm (a fungal infection) or skin mites.
Ideally, we would have Ripley seen in person so a vet can examine the skin and ears and take any necessary swabs to look at under the microscope.
If this isn't possible, there are a few things we can try at home.
I would use Xeno spot-on, which is a topical Ivermectin that should eliminate any parasites. Do also deep clean the housing at the same time. You can get this from Pets at Home or Amazon.
You can purchase Chlorhexidine (Hibiscrub) from a chemist (e.g. Boots or Superdrug). You dilute it 1:10 with water so it is pale pink and apply a small amount to the affected areas for 5 minutes each day with a cotton bud. After, use a wet cotton bud or cotton wool to rinse the fur. No need for a full bath! This is done for 5 days and can help to treat bacterial or fungal infections.
Consider trimming the claws short if very sharp, though only if he will let you.
It can also be sensible to try and keep him occupied when you can with different games and toys to play on.
Finally, try to think if anything has changed recently e.g. his food or bedding, as he could have an allergy to the new product.
If his signs continue or worsen, a vet visit would really be for the best.
I do hope this helps!