Integration in the webpage is smooth, but the add-on only takes the first few videos into account and does not work once the playlist is running.

Esta extensión no calcula muy bien la duración total, aún haciendo scroll como dice el autor. Hay extensiones que funcionan mejor.

Amazing extension! Works perfectly!

This add on is great because it's the only one that does what it does on Firefox, to the extent of my knowings.
It would be perfect if the amount of time calculated could be displayed in a better place than the playlist's page description and the display should stand out more instead of hiding in the same font.
Also it would be awesome if it could count a selected number of videos into a sum of video length.
Thanks for making this!

Awesome extension. Would give it 5 stars if it also shows the total time left for next videos in the playlist when you play a video (that is, when the playlist is on the right side of the video page).

Thank you for creating the addon! It works as intended, is small and very simple. It essentially lets me know when I put too much vids in the playlist, since their additive length isn't obvious to me without exact calculation. It even displays the time for Youtube QUEUES, which are relatively new feature! :D

However, I've found a conflict with another addon, where it's only displaying "Total Duration ( )" with no time specified: it happens when the "No Playlist Autoplay For Youtube" addon by T Rich is activated.
I don't know how the stopping of playlist/queue autoloading is relevant at all to the calculation/display of time since the videos' lengths are given with no change.

When the playlist length is more than 24 hours, I think it should display days too, lol. No, seriously, this is going to be an useful sanity check for some people. ;)

I also think it would be better if the way the time is displayed was configurable in the options, because the purpose of the numbers is obvious and after a while the phrase "Total Duration" only adds to the space used & gives no useful information. It actually fills almost the entire space between "+SAVE" & "CLEAR" on the Queue because of it.
Potential user could also want to have different time formatting, be it "1h, 23m, 56s" instead of "hours, minutes & seconds", or even going full "1:23:56" if they like.
Since it would do good for the addon to keep it simple, you could just add checkbox options for the formattings mentioned above instead of going full regex on the user if you want, because that would add some complexity to setting up the addon. I consider the regex level of control to be a bonus (but yeah, having the parentheses [square] would add some readability for me, so that could be an option too ;P).
Or maybe you could create the default simple-config, and the "advanced" checkbox that disables the simple config & lets the user set whatever they want via something close to regex - but again, that's a bonus.

Overall it works well, but there exists possibility that:
- it doesn't update the time if I pick another playlist from the left-hand-side Youtube menu list, when I'm in the youtube.com/playlist?list= view. This is because Youtube somehow loads it in place the same view without actually making the browser behave like it's "goign to another page".
- it also doesn't update when reaching the bottom of the list, since the Youtube loads only first 100 videos & to load more you need to go down, but your addon is stuck at showing the time for whatever was on display before it has finished loading after the page refresh.

I thought it was the default behaviour and I figured re-enabling it gets me what I want, but it turned out after a few such actions that it actually updates them as they come, which is your intended behaviour. I don't know wtf. Maybe sometimes it gets clogged/overloaded or when the browser session has too many tabs (but they're suspended & not from Youtube) it can happen because of some browser memory problems if it gets too heavy?
So maybe let the user click on the time displayed to re-calculate the time? The time displayed is already looking like it's some sort of a link, but it doesn't do anything when I click it. :O For now, when the above happens, to get the time of loaded list I need to disable & re-enable the addon manually - thank you it doesn't need to reload the page to trigger & show itself there!

There are also cases when it seemingly doesn't trigger at all, not even displaying any text as if there was no addon, but I don't know what causes this exactly. I might do some testing, but I don't know what to look for. I might write you an email if you think this is better channel for communicating.

So if you make it work with the autoplay stopper, add some formatting customisation & make it re-calculate the time on click (for when it doesn't update automatically), it will basically have no fault & using it will make me so happy. Or if you have other ideas for those problems!

But yeah, this is a very good addon, it aims to do exactly what I wanted, I recommend it! ;D