When are some anti-arrhythmics contraindicated?

Watch the video below of the 2 cases where giving an anti-arrhythmic, or a particular kind of anti-arrhythmic could kill your patient.

WHAT do you think those two cases are?

1. AF with WPW and giving an AV nodal blocker and 
2. Hyperkalaemia and giving anything that will poison the Na channels like Amiodarone.