How do you think the Thanes around the table are feeling after Macbeth's outburst and Lady Macbeth's hasty dismissal of them?
In the context of the Elizabethan thought, the appearance of a ghost is extremely disconcerting since the presence of the supernatural world is always taken seriously by the people of this era. In an earlier era, such as that of the setting of Macbeth, it seems reasonable that people, also, would be affected by bizarre activities. In Act III, Scene 4 when Macbeth abruptly addresses something that does not appear to the others, the Thanes, one would suppose, would be rather disturbed themselves. Of course, Ross immediately suggests that he and the others depart as "his Highness is not well." And, although he remains because Lady Macbeth explains her husband's behavior, he yet wants to know what it is that Macbeth has seen: "What sights, my lord?." Certainly, when a king shows signs of mental disturbance, there is a doubt created in the mind of his subjects.
Well, based upon their comments, the thanes do not feel anger. One feeling they express is uneasiness for Macbeth's seeming illness: "Gentlemen, rise: his highness is not well. /... / Good night; and better health / Attend his majesty!" Another dominant feeling is disconcertedness as they have no answer to nor understandings of his demands to know who did what they are not aware of:
Finally, when Lady Macbeth dismisses them, "Stand not upon the order of your going, / But go at once," they must feel foreboding as to the import of this unaccountable behavior and "illness" that has stricken their new King--foreboding that tends toward alarm and suspiciousness.
I suppose you are looking for a personal opinion. Certainly the thanes are confused by Macbeth's actions, but they are easily placated by Lady Macbeth's explanation. It is likely that the thanes know little about Macbeth personally--he was chosen to be king based on his reputation as a fierce and loyal warrior-- so they are willing to take the explanation at face value. Besides, what reason has the good Queen to lie?
To a certain extent, however, it doesn't really matter what the thanes think about Macbeth. The reader's focus should be on Macbeth's mental anguish and guilt over Banquo's murder. Lady Macbeth facilitates that by basically telling her husband to "snap out of it" and keep his ruthlessness intact.
The Thanes would obviously be feeling very confused and curious about Macbeth's outburst. At this moment in time, Macbeth is still looked up to as the King of Scotland and is very well respected, the Thanes would have been concerned for his mental health, as they did not understand at the time that he was seeing Banquo's ghost. They also expressed distraught at the helplessness and confusion they were feeling watching this scene take place and not knowing what to do to help his highness.