That is a very bad design with "shoot through" and should be avoided.
That circuit shorts the supply rail to ground HARD every time it switches over, potentially pulling20 to 100A from your LiPo - no wonder the wires get hot!
I am using irf630 and irf9630 mosfetsfor my H-bridge circuit. The problem is, when both the battery and the arduino are connected, the circuit doesnt work. However, if i put my finger on any one of the transistor (mosfet), it starts working. please help.