Video (mp4) small but longer prproj length

Hello,
Please created my first "prproj" using Adobe "Premiere Pro - Version 13.1.5 (Build 47)". Sorry if I type something other than the appropriate language for this program. In addition to other initial learning questions, I request help with the following:
1) I picked up a Youtube video at this address: https://www.youtube.com/playlist?list=PLiunUVYbYe488zFC8D75YvNk3Vss_pQew.
The total length of the video is 00:59.
2) I saved in the "prproj" folder as "Cloud Sky.mp4" and dragged it to the corresponding line;
3) It turns out that my "prproj" has a duration of 00: 43: 24: 02 and, thinking it would be fine, I dragged the "Cloud Sky.mp4" until it reached 00: 43: 24: 02. Is it good? I thought so, but I understand that there is something to be done to improve the presentation;
4) The clouds passing in the sky when you change from one "Cloud Sky.mp4" to another the result is bad, that is, it is not the same as the original YouTube.
5) I searched and really have examples on the internet, but I still can't learn how to make the effect of switching from one mp4 to another does not appear so much change. Could "mp4" be increased? I clicked on that option to lengthen the video on YouTube, but saw no result.
Thank you for your attention.