Here's part of an article that may help to answer your question (I hope) ...
Testicle Movements And What They Mean
Another reason for testicle movement does have to do with sexual arousal. In the 1960′s, Masters and Johnson observed that the testicles elevate just before ejaculation and actually make direct contact with the body. They found that in about 85% of men the right testicle rises before the left one.
Masters and Johnson stated that this movement is very important and that at least partial elevation must occur in order to have what they called a full ejaculation. Sometimes older men will have varying testicular movement and report that there is less pleasurable pressure associated with their ejaculation when their testicles elevate only slightly. Younger men can also have the experience of less pressure when they ejaculate involuntarily and before arousal has reached its peak.
During arousal the testicles also increase in size due to vasocongestion, the accumulation of blood in the pelvis that occurs during arousal. The skin of the scrotum thickens and the testicles increase in size usually by approximately 50% at the height of arousal. However, Masters and Johnson found that if sexual excitement is sustained long enough, the testicles could almost double in size, returning to normal size after orgasm. They also found that this increase in size tends to taper off as men age.
So, the answer to the question about arousal is a qualified yes. Some people watch their partners scrotal elevation as a sign of how close he is to reaching orgasm. This is more easily done during oral and manual stimulation. Men looking to last longer, can also notice this aspect of their arousal to determine where they are relative to orgasm.
:biggrin1:You can read the full article here:
Testicle Movements – And What They Mean