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Thank you! I understand it now.

Thanks Janus! That was helpful. A few questions though - am I correct in understanding that in the formula you described, v1 (velocity of the car) is relative to the initial reference frame (in this case the road/earth), and v2 (velocity of light) is relative to v1? And Vt, as the function of V1 and V2, is relative to the initial reference frame?

http://www.youtube.com/watch?v=aZrjMmMBa_8 Time dilation in the context of the theory of relativity does not seem to make sense to me. It is based on the premise that the speed of light is constant, which is said to be an exception when discussing relativity. For example, as demonstrated in the video above (5:00 to 8:00), the distance traversed by a particle of light that is emitted from a stationary car is said to be 'd=ct', whereas when such a particle is emitted by a car moving at velocity v, then the distance traversed by such a particle is represented by the formula d=(v+c)t, because the particle already possessed the velocity of the car when it was emitted. After this is explained logically in the video, it is said that in case 2, since the distance has increased, time must have increased as well. But clearly, the increase in time is due to the addition of 'v'. I understand that if the distance equation in the second case uses 'c' instead of 'v+c' as velocity, then it is reasonable that the time should increase, if this phenomena is observed by a stationary observer. Why is it an exception that the speed of light emitted from a source does not depend on the speed of the source? If the same principle is applied to every other body, why is light exempted from it? It would be great if someone could explain this to me, or provide resources explaining this.