@Irene777 - Some time ago we removed all HTML code from lessons, as these caused issues when saving LingQs. Instead, I recommend adding URLs through the Notes feature found in the Select Resources menu when editing a lesson. You can also use this to write notes for lessons where applicable.
Your screencast is so good that I could work it very well.
The problem is only the following: If I open the URL in the item, I cannot have both things side by side, and I cannot switch from the lesson to the picture and back. If I open the URL, the lesson is no longer available.
Do you have a clue how the way back (from the URL to the item) is possible? Or do I anything in a wrong way?