Matty began the YouTube channel GiantWomanMusic in 2015 to promote the cover band Giant Woman which covers songs from cartoons. The channel started making reaction videos to the cartoon shows "Steven Universe" and "Gravity Falls" as a way to further promote the band which covers songs from cartoons. These reaction videos featured Matty and Abbie who is a member of Giant Woman and not, as some had assumed, someone with any relation or other connection to Matty.
The reaction videos became much more popular on YouTube than the music, which was popular on Spotify, so eventually the channel rebranded as Mattytime since the name "Giant Woman" became confusing as videos began to feature only Matty and grew to include content such as vlogs, gaming videos, and skits.
In most videos Matty wears a red t-shirt or hoodie with a yellow star on it (the shirt of the titular character from "Steven Universe) and a blue and white cap with a blue pine tree logo (the hat worn by Dipper Pines on 'Gravity Falls). Occasionally he wears a yellow Pikachu hat.
Mattytime also has a gaming channel with much less subscribers and a separate channel for content related to the band Giant Woman.
Matty is a member of a loosely organized group of YouTubers who call themself "Clods" that make similar content. A group that includes IAmZamber, Fenix, Spooked, TheCartoonKitty and others.
The band Giant Woman began when Matty joined forces via facebook with original lead singer 'Sara G." to cover the theme song to Steven Universe. The response to that track was positive and soon became the side project of the Boston based band "I'm Gonna Go To Sleep" of which Matt was the producer. Covering songs quickly became the creative focus although members of the band didn't see the potential in that style of music. Matt eventually broke up the band when another member of I'm Gonna Go To Sleep disparaged creators making similar cover songs and made negative public remarks which Matt didn't want associated with what was otherwise a friendly and community-focused project.
Giant Woman became more known on YouTube for reaction videos in which Matt and current lead singer Abbie watch episodes of Steven Universe and Gravity Falls. Abbie wanted to focus more on music projects instead of YouTube and both were frustrated with the audience often assuming that they were related in anyway, so the former Giant Woman channel was rebranded and new channel was started to host videos only relating to the band. Giant Woman has collaborated with YouTube singer Princess Rizu and a producer working under the pseudonym Tripcaster.
The Giant Cartoon Show
For most of the channel's history, reaction videos were labeled as a series called The Giant Cartoon Show which featured a short theme song sung by Matty which the simple lyrics "It's the Giant Cartoon Show, We'll make a real theme song soon". The original format consisted of comedy skits and improvised vlogs leading into reacting to an episode of a cartoon and then following it up with discussion about the episode and its creators. These segments were shortened and eventually dropped.
When asked during a recorded 2017 livestream why the videos no longer had the theme song he answered;
" I used to put so much work into those videos. I was really proud of the skits and segments sharing fan art with everyone. It really helped me justify what was otherwise sort of weak content. I didn't want my channel to degrade into something like Jinx or whoever. But I started getting [really] frustrated with people who would post timecodes in the comments so people could skip over all my work... ...and I could see in the analytics that 90% of the viewers were skipping over the content that I spent 90% of my time making... it's a real kick in the crotch. Even videos that have no skits or vlogs and only had the theme song, people were skipping over the 15 second theme song. I didn't feel that the later videos that just start with me watching someone else's work really deserve a theme song. The Giant Cartoon Show will still be a thing, but not short reactions without any of my own content."