|Source: George D|
I don't interpret the latter as an actual knee break. It's true that this technique appears in older karate manuals, but the breaking palm should be in front so as to apply more pressure. See the technique shown by Kenwa Mabuni below.
|Kenwa Mabuni's knee break from Karate Do Nyumon (1938)|
|Sources: DTDT, Rogue Warriors|
Grab their left leg with both fists. Then step through and turn while pulling up the leg with the inner-forearm wedging block, tripping the opponent over your rear (left) leg. This is shown in the gif below.
Double Side Kick
Low Target Hammerfist
Cross-step side kick (Richard Conceicao)