Wa `alaykum as-salamu wa rahmatullahi wa barakatuh.
In the Name of Allah, Most Gracious, Most Merciful.
All praise and thanks are due to Allah, and peace and blessings be upon His Messenger.
In this fatwa:
1- While fasting, a Muslim should train his soul to bring himself near to Allah by doing as many good deeds as he can and refraining from even wasting his time in valueless deeds.
2- Listening to music and watching movies, etc. while one is fasting may fall under the categories of either sins or idle deeds or behavior.
Answering your question, Sheikh Ahmad Kutty, a senior lecturer and Islamic scholar at the Islamic Institute of Toronto, Ontario, Canada, states:
Fasting in Islam is a great spiritual discipline. Its primary objective is to train the faithful spiritually and morally. Therefore, in order for us to reap true benefits of fasting, we must not only abstain from food and drink and sexual relations from dawn to dusk but also must shun all activities and behavior that are inimical to the spirit of fasting. Proper fasting involves guarding our eyes, ears, hands, feet, as well as our mind against sins.
The Prophet (peace and blessings be upon him) said, “Whoever does not shun foul words and acting accordingly, there is no need for him to deprive himself of food and drink.” He also said, “Fasting is a shield (against sins or vices); so if one of you is fasting, let him not engage in wrangling or foul deeds and idle talk. If anyone scolds or ridicules him, let him not retaliate; rather he should simply say, I am fasting, I am fasting.” (Al-Bukhari)
Listening to music and watching movies, etc. while one is fasting may fall under the categories of either sins or idle deeds or behavior. According to `A’ishah, the beloved wife of the Prophet (peace and blessings be upon him), as well as great Imams such as ِم-Awza`i and a number of scholars of the pious generations, activities such as backbiting, engaging in gossip and idle chats will render one’s fast null and void.
Therefore, in their view, those who are guilty of such behavior must make up their fasts. Although the majority of scholars do not share the same view as far as breaking the fast is concerned, nevertheless, they also concur that such activities do take away true rewards and blessings of fasting.
It is, therefore, imperative that we abstain from such behavior altogether. May Allah help us preserve the sanctity of Ramadan. May He help us to use the great spiritual season to break ourselves free of such habits.
Allah Almighty knows best.