To calculate the cost of an additional movie package for 13 months at a rate of 8 dollars per month, you would multiply the monthly cost by the number of months:
\[ \text{Total Cost} = \text{Monthly Cost} \times \text{Number of Months} = 8 , \text{dollars/month} \times 13 , \text{months} \]
\[ \text{Total Cost} = 104 , \text{dollars} \]
Thus, the total cost for the additional movie package for 13 months will be 104 dollars.