Resolved autoplay of video and made only relevant changes #1308

[Vinit1014]

PR Fixes:

• 1 Autoplay next video after completion of one and also handled the case where "week 1" last video is played then "week 2" first video is played.
• 2 When last week's last video is played then it doesn't route anywhere instead stays there.
• 3 Implemented the same autoplay next video with the "Next button" and while reaching last week's last video disabled that button and showed the message "Last video of the course".

Resolves #1308

autoplay2.mp4

Checklist before requesting a review

• I have performed a self-review of my code
• I assure there is no similar/duplicate pull request regarding same issue