This video says about itself:
Believe it or not but this long thing isn’t adult yet… it gets twice the size. Spieces: Phobaeticus serratipes Instar: 5th Gender: female Length: 30 cm
Translated from Groninger Internet Courant in the Netherlands:
This species may reach about 50 cm long, including the legs. The longest insect, also a Phobaeticus species, is 55 cm. The animals here, juveniles still, are already over 30 cm. Newly born animals, called nymphs, are already about 8 cm.
Some of the strangest (and large!) insects in the world: here.