Basically, in regards to locations in HTML (img src, form action,a href etc) you will need to make the link in respect to the file that is ultimately calling the file with that information. So if you have your http://www.sanjayshahseminar.com/temp/index.php with an include for http://www.sanjayshahseminar.com/temp/videos/video.php - any references to file locations in HTML tags will need to be as if you are typing it in the index.php, as it is only in this point that the HTML is printed and parsed.
Whatever page you are on when you see data, the paths should be as of that path (ignore the location of the php file - if file2.php being included in index.php and they are 3 directories away, the img paths would still be the same, whether it was in index.php or file2.php because even though the php files are in different locations, the location at which the HTML is outputted is the same).
Hopefully this clarifies? If it doesn’t don’t worry, you will understand eventually, it just takes some time to get used to.