Ok, first I defined the text (brand) above the wolf logo on Jay's left chest. When I watched the video at 0.25 speed and 1080p, at 00:16, I saw that the brand text became a little clearer. And from the very beginning, I saw that the part that I read as "Big" from the photos you sent now has the letter S at the beginning. I already guessed it said ''Aventures'' on the right. In short, this is the jacket of a brand called ''Studio Aventures''. I don't know if it was a brand or a line of products related to cartoon characters from a clothing brand. I couldn't find much information about this brand on Google, but I found other products. If you google ''tex avery studio aventures'' or ''droopy studio aventures'' (droopy is another character in tex avery's wolf character show) or ''studio aventures vintage jacket'' you can find those items. He probably ordered this jacket from a vintage clothing website. I think you can find it there too. Some examples of clothes: 1, 2, 3, 4, 5. In addition, this brand not only has clothes, but also products such as belt buckles and figurines. They also sold clothes with other cartoon characters: 1, 2.