I think I should probably give some details of what went on with goAnimate, because I was there when the HTML5 transition occurred.
About Alvin Hung. I understand many people's hatred toward him for SUPPOSEDLY being responsible for the controversial HTML5 transition and removal of themes. Heck, I was among those people once. Currently, I think he (in ties to the site) is innocent and had nothing to do with the controversial transition. I have evidence to support he left the GoAnimate team just before the start of the transition.
According to Wikipedia, Hung is listed as the founder and FORMER CEO of GoAnimate/Vyond. Gary Lipkowitz is listed as CEO. Obviously Hung isn't part of Vyond these days. Some Goanimate wikias on FANDOM say he lives in Hong Kong and is a current adviser at Wing Han Manufacturing. If anyone can get more reliable sources on this, that would be great.
The most telling thing that shows Alvin Hung left GoAnimate is his Twitter, which was exclusively for the GoAnimate site.
His last tweet was on Sep 2, 2015, which was an announcement that Business Friendly was introduced to G4S. Before this day Business Friendly was just another theme, not meant to replace the rest as it was known for doing in the HTML5 transition. The tweet before even shows a Lil' Peeps character alongside one from that billboard theme.
Notice I said "Before this day" above. Although the official announcement for the HTML5 transition was made on October 19th of that year, preparations were starting to take place around the same time of Hung's last tweet. I can't find the post in question, but please take my word for it. I think on the same day Hung posted that tweet, a user made a post on a blog related to GoAnimate. In that post he noted the non-buisness video makers were shunted off the main page and asked staff member Mark Deaton via email what was going on. Deaton stated that they were planning to transition to HTML5 and were reviewing the themes.
I'm pretty sure Alvin Hung left because he didn't approve of the direction Goanimate was heading in. That's my educated guess. I'm not bashing on Alvin Hung here because he obviously didn't contribute to the controversy. I'm just leaving some information that could contribute to the article.