Is there a difference in the halacha in hearing a woman’s voice singing on a video and live?
According to the great majority of poskim, there would be no difference.
Some, however, do make a distinction, and might consider seeing a singer on video as being more lenient than live, but I have not seen any poskim who permit the practice.
Hearing the singing voice of a woman on the radio or on a tape (gramaphone, disc, etc.) is a widely debated question among poskim. Some write that this is permitted, because a person is not brought to lecentious thoughts by the voice of a woman he does not know (or see). Others are stringent. Below is a partial list of both camps:
Lenient: Beis She’arim (2:33), though he writes that it remains improper (and mechu’ar); Tzitz Eliezer 5:2 (based on Mateh Moshe and Raviah), though he stipulates that one should not have intention to enjoy the singing; Yabia Omer (1:6); Halachah Berurah (75:15); Benei Banim (2:11; 3:127).
Stringent: Peri Hasadeh (3:35); Chelkas Yaakov (Orach Chaim 6); Shut Ravaz (teshuvos from author’s son, no. 6); Shevet Halevi (3:81); Az Nidberu (9:9).
See also Chayei Asher (104) who mentions both sides of the issue. A number of poskim add that there is room to be lenient concerning a recording, and less room for leniency concerning a live broadcast (radio): see Be’er Moshe 7:109; Hayam Hagadol (29). Some have expressed wonder at this distinction.
The poskim listed in the lenient camp make a point of stating that if a person knows the singer, or has seen her picture, it remains forbidden (see especially Yabia Omer). The entire leniency is based on various sources that imply that a person is led to improper thoughts by his eyes, or by what his eyes have already seen (see Sotah 8a; Megillah 15a; see also Berachos 57b and Rashi). If a person knows the singer, or has seen her picture, the poskim are therefore stringent.
Yet, Tzitz Eliezer mentions an additional reason for leniency: a voice on the radio or tape is not a true voice, but rather electronic signals that are translated into voice (see also Benei Banim). According to this rationale, the same would apply to video recordings. However, Tzitz Eliezer does not refer to video, and only to audio, where we have the additional reason of a person’s not seeing the singer, and it does not appear that he would have been prepared to rely on this rationale alone.
Therefore, seeing a woman singing on video would remain prohibited, but it might have a leniency over seeing a live concert.
See also Sedei Chemed (kuf, no. 42), in the name of Divrei Chefetz, who writes that not all forms of women’s song are prohibitied, and if she sings praises of Hashem, or mourning songs, then there is more room for leniency. Sedei Chemed does not accept the ruling.