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@mountainbikermark and
@cr6 are right. Depending on how fast a connection you have now, watching a YT video should be free from stalling and so a 5 minute video should be 5 minutes, as MBM mentioned. At the same time, in a throttled data connection there could be playing that exceeds the rate of buffering, causing stalls in the play while the buffer has to refill and catch up. It all comes down to data rate versus frame rate. Each frame in a 30 FPS video uses a set amount of data and so in one second of video the stream will use 30X that frame data amount. Unless the data rate can keep up the buffering will occur. You can be sure it will occur for some while being throttled. The depth at which they throttle may be minimal initially or for most, but they reserve the right to throttle to an equivalent rate of 2G. That would certainly result in buffering of a YT video.
As for the costs for new 5G network, and the OP's initial question below;
"...What happens when XLTE or 5G which is really 100x faster than current LTE speeds (can be upwards of 60mbps in my area in Central NJ) is deployed in it's entirety? The cost of overages will be shifted to current and new customers, as most users will eat into the data cap so much faster at a higher bandwidth speed."
Truth is 5G can be as much as 100X faster, but will roll out at no where near that level of increase. It's more likely to be rolled out at maybe 10X to 30X faster initially, but can certainly be ramped up as the network sees fit. It's not really accurate though, to say users will eat into the data cap faster, unless they are doing things like downloading video or audio to hoard it, or who choose to use their cellular data service as the source for their laptops and desktops.
"I know I'd be doing a lot more YouTube and Pandora, besides gaming. It kind of worries me that the cost of these plans once you go past the XXL plan prices rise extraordinary. Even with the carryover and safety mode option, how good of a product can you get on throttled speed?"
Yes, costs above XXL rise quite significantly but there are very few people who will need such high data packages. Also, if you are smart about your data use and WIFI when and wherever possible you will keep your paid data to a minimum. Still, throttled will be for many a very slow and painfully uncomfortable rate of data. It's not meant to provide a continued user experience comparable to 5G or 4G, and even may not provide a 3G experience, if Verizon chooses to go to the lower limit they've set for themselves.
For the costs of overages to be put onto the shoulders of those who use the data in such a way as to exceed their pricing plans, that is just how it should be. I don't want to subsidize your data, and I'm sure you don't want to subsidize mine. If I use 10GB or 100GB, I will pay the same, however I risk (now), losing my UDP altogether if I use the latter. If I either choose to, or am forced onto a tiered plan you can bet I will do two things... First, I will buy the plan that provides me sufficient buffer above my average data usage so that I don't fear going over, but second I will add the Safety Mode and if I hit it I may at that time increase to the next level up in the plan offerings.
Today I checked and I could get 40GB for less than I am paying now for UDP. I use an average of 24GB, even taking into consideration two months of extremely exceptional circumstances, where I used over 30GB followed by close to 80GB the next month. If I take those two months out of the average then I'm running at about 9GB so 40GB would be quite a huge margin to protect me from overages and from throttling.
