About the backbone

[pencilYi]

Thank you for your contributions!
Could you tell me:
def forward(self, xset): B,L, _,_,_ = xset.size()
1.What does the 'B' above denote?
2.Does the 'L' denotes the number of frames' features?(Is the 'L' above as same as the 'L' in the paper's Figure.3?)
&
`class TemporalAlexNet(nn.Module):
configs = [3, 96, 256, 384, 384, 256]

#input (B*L)*C*W*H, A1,A2,A3,A4,B1,B2,B3,B4...`

Could you tell me more details about the structure of the inputs and outputs?