To fellow Sony KDL-60EX645 owners,
I got the app to half way work normal again. After days of trying: power resetting, app refreshing, loading videos - stopping them - reloading them...I finally stumbled upon what issue was. Some type of memory buffering error (just a best tech guest) where the app couldn't clear memory out fast enough or got stuck clearing it out.
I loaded a short music video (in this case Skye Sweetnam's Tangled up in me, 2:52). It was a short video in non-HD and somehow because of this, got the memory to load properly (I was playing a lot of long HD videos on YouTube before this).
Great news! Stumbling upon an old standard definition pop classic from the early millennium resolved the error!
I hope this work around hack will work for you if you're experiencing the same issue with the KDL-60EX645.
Another odd issue still exists, I can't play long HD movies from my "Purchased" category, it just freezes with the words "Loading."
I can play short and some long SD and HD videos again (except for purchased movies). So half the problem solved?
Please share if you had a similar issue and resolved the app issue completely. I would appreciate it. I'll keep updating until the app fully works again.