By Sam Elliott-Gibbs Members of a notorious Mexican cartel were seen laughing as they watched a National Guard helicopter plummet to the ground killing three people. The aircraft, carrying three soldiers and a Border Patrol agent, crashed near the southern border in Texas. After the chopper burst into flames, the group was captured on camera roaring and hurling insults. Footage from a US Customs and Border Protection agent shows cartel members watching the servicemen’s final moments. Two soldiers and the agent perished in the crash, authorities confirmed. A third soldier had a miracle escape b…