and what is if you live in el salvador and got payed in BTC? or if you travel from europe and change your EURO for DOLLARS...if you enter in a shop and pay with dollars you are countertrading in euros?

1) The article explains that 'getting paid' in El Salvador in BTC is countertrade

2) Both Euros and dollar system are pricing systems. BTC is not. So the answer to your second poing is no