Engadget adds that the 4G in myTouch 4G is likely in reference to their HSPA+ network which T-Mobile likes to tout as having 4G like speeds.
Below is the video (correctly oriented) thanks to Android Central:
Regarding the HTC Glacier details, AndroidandMe notes that at the site which revealed the ROM, references are made to the HTC Glacier and myTouch 4G being the same phone. The Glacier was rumored to feature a dual-core processor based on some benchmarks we saw earlier, and a leaked T-Mobile document at TmoNews mentions the myTouch HD (which appears to be the myTouch 4G) also mentions a "1GHz dual processor", which could easily be a typo for dual-core processor.
AndroidandMe also mention that the ROM in question is labeled as "For Glacier / US T-Mobile 4G" and that they haven't been able to confirm anything yet, as the download of the ROM has not yet finished for them, so the haven't had enough time to get digging around inside the ROM. They add that "once the download is complete, we hope we’ll have a few more details to share."
Phandroid remarks that the Yahoo Messenger video chat app contained in the myTouch 4G ROM, according to XDA-Developers, "works great for EVO to EVO video-calling over WiFi" but couldn't get any compatibility between EVO and Yahoo Messenger for Mac.
Head over here for the Yahoo Messenger video chat app.
Image from AndroidandMe