I know this is an older video and maybe you already covered this in a future video but in the beginning, before the 2 min mark, you were unable to create a model line. You should have used a detail line instead, it will allow snapping and can be drawn on any view, its not reference plane specific. Model lines should be used sparingly and deliberately, same does with reference planes/lines. Detail lines are a lot more forgiving and do not really affect the model the way the others mentioned do.
I know this is an older video and maybe you already covered this in a future video but in the beginning, before the 2 min mark, you were unable to create a model line. You should have used a detail line instead, it will allow snapping and can be drawn on any view, its not reference plane specific. Model lines should be used sparingly and deliberately, same does with reference planes/lines. Detail lines are a lot more forgiving and do not really affect the model the way the others mentioned do.
Amazing content!