A comment on "Hi, I'm Steve" said that the video was depicting the life of a depressed schizophrenic who the video shows gradually mentally destabilizing because he is not happy in life. The comment then goes on to state that the video is told through Steve's eyes and the "random bursts into jingles" show how "childlike his mind is". The mountains are categorized as his mental issues, which he can't climb, but due to the mail (medication) that the girl mailman (doctor/nurse) delivers to him helps to mask these issues to help it look like they are working. According to the comment, he then states that he can suddenly climb the mountains, proving that the medication is appearing to work. The rain at the end implies depression which is the result of the medication not helping Steve. The weather forecast at the very end depicts that he will have this depression forever, and the final line, "Bye, I'm Steve" shows that he is not happy with life and kills 
 himself.
  I'd like to know your thoughts on this theory. All credits for the comment go to shredup chopel.