Watching Mass on TV is not the same as attending Mass and does not fulfill someone’s Sunday/Holy Day obligation. However if someone is unable to attend Mass then there is no obligation to attend Mass (one cannot be obligated to do the impossible). Being with the community of faith and in the presence of the Eucharistic Lord is not the same as watching it on TV. After all, would you consider internet video chat with a loved one the exact same as being in the same room as them?
Now, even though they are not the same does not mean watching Mass is without merit or benefit. Continuing with the internet analogy, if you’re unable to to physically be with someone being able to see them is a good second best. Watching Mass on TV someone can reflect upon the readings, hear the homily, pray along with the community at that Mass are all good and pious things that bring spiritual benefit. However that benefit is not the same as being present with Church and the Lord and receiving Him in communion.
