I think we are looking at a braided nylon rope, not an electric cord. It's just too new looking to be a vintage cord such as one finds on older appliances as toasters, fans, coffee percolators, etc. It seems to me that it was domestic irons that featured the really pretty colors to match the trims in the 1950s until rubber sheathed cords became the norm.
None the less, Dean, the only way such knots would be produced would be during a particularly vigorous round of vacuuming that had the machine crossing and looping over it's cord coil that would then be teased into a knot as the vacuum was pulled to another room at the limit of reach before yanking the plug out of the wall socket - I've had that happen with Shop Vacs.
Dave