Did you push the root tabs down into the substrate? That is how they work. I would also assume that this time lapsed video is with a CO2 injected system. It also depends on what the plants were. What type of plants do you have? Are they stem plants like Hygrophila, Ludwigia, Bacopa, Rotala etc. Or, are they rosette plants like Cryptocoryne, Echinodorus, Valisneria(long leaves that come up from a central point with roots below)? Or, do you have rhizome plants like ferns and anubias? Root tabs help for stem plants but, a liquid fertilizer would be a better option because most stem plants obtain nutrients directly from the water column. For rosette plants root tabs will be the best option as they go below the surface of the substrate where the plant's roots will have access to them. Again for rhizome plants a liquid fertilizer will be your best option as they attach to things like rocks, gravel and wood and obtain nutrients primarily through the water column.
Stock lightly and carry a big filter. - I don't have aquariums. I have ecosystems in a glass box. - Hygrophilaholic and hoarder of Anubias.