I have heard this many times as well, and wondered the same thing. I copied this answer from SpanishDict.com answers, which seemed to give a pretty good explanation: "It all depends on the location. For example, in Medellin in Colombia, yo is pronounced jo. Actually almost any word that has a y sound (both Y's and LL's) is said like a j or something like shz. That is why there are also two ways to say Medellin: me-de-shzín / me-de-yín. The funny thing is, I have heard some Colombians ask me "Jes or no?" because they think that all y's are said like j's. (Personally, I think the sound of J in Spanish is beautiful, so I use it, but in reality it's not that hard to switch back to Y.)"
I hope this helps!
They have awful voice "actors" or whatever you want to call them. From "Yo" sounding like "Joe" to (in this can) you CANNOT hear "en un"... it's so "mumbled" or "slurred" and sometimes it sounds like they just skip it all together and say "Yo vivo apartemento". I have a good ear for the most part, but this is one of the few things that is THE ONLY reason I have to slow it down. For a free app I know this is asking a lot, but I feel they need to re-record a good portion on this.
In plenty areas they spell y like j so this is correct and you're incorrect, you shouldn't assume they spell it like you do in English, it's a different language. And native Spanish speakers do talk fast so it prepares you to understand real life people who speak Spanish.
Hi David thanks for your comment. I agree that staying indicates something temporary, but what exactly that means is not certain as someone might often comment something like "I stayed there for three years"... I wonder if "vevir" could take the same meaning and if so would be a valid translation. Else is there a Spanish word that are similar to stay?