Flyback converter small signal AC model

[Patrick66]

Hello everyone, I would like to ask why the small signal AC model is different in obtaining the transfer function of the flyback converter from the YouTube video that I saw (Link below) compared to the article (Article below)  that I read? Are both methods of analysing able to be used or either one of the methods is wrong? Hope that someone can help me with this thank you very much for your time.

Youtube Link:     (explanation around 9:07)
Article: Attachment below

[moffy]

So many posts on the same topic asking some very broad quesions e.g.
this one.
https://www.eevblog.com/forum/projects/pfc-modelling-in-dc-dc-converter/msg5355569/#msg5355569
https://www.eevblog.com/forum/projects/type-two-compensator-in-flyback-converter-for-led-driver-in-dcm-mode/msg5369618/#msg5369618
https://www.eevblog.com/forum/projects/how-to-obtain-the-specific-component-in-ltspice/msg5353199/#msg5353199
etc.
getting hard to keep track of.

[Patrick66]

Sorry about that sir because I wanted to study how the whole system works through the YouTube video and there are a lot of things that I didn't understand from the video but thanks to this community, I was able to understand the video. Now the problem is I found an article which is similar to the Youtube video that I saw but the method of analysis of the system is different so now I'm confused about which method of analysing the circuit is correct or both will also produce the same result? Maybe because the method of analysis that they use is different? I'm not sure about that thus I wanted to seek help from the experts. Once again sorry for posting so many posts related to this study.