I live in a large shared house with with several roommates. The company that owns the house tries to rent it out to international people (however I am not international myself).
If the landlords like to get international tenants, then you can fully expect the others to not speak English. From the point of view that this is one of your "issues", the simple answer is: Don't live in an environment such as you do, if you find it unpleasant.
Many people I live with do not seam to make an effort to speak English, though several of those who seem not to want to speak it fine when they do.
Unless they have a reason to need you to understand or are speaking to you, why should they? If whomever they are speaking to is the sole intended recipient of their conversation, there's nothing wrong with this.
Several couples have been bringing laptops into the kitchen/living room and listening to videos or podcasts on them. I find the additional noise, often in a language I do not understand, unpleasant.
Firstly, unless this is a case of them taking up all of the space, for long periods of time, with the noise being excessively loud (i.e loud enough that it can be heard in your own room or other communal areas to such a degree that it cannot be blocked out or avoided during a period in which you can't go somewhere else)- then this stops being an issue of being unfair, but of your personal preferences.
If it's too loud, ask them to turn it down. If it's in another language, this is a moot point- you aren't involved. If it's for too long, speak to them about fair usage of the common areas.
Also the fact that they seem to be occupying a table in the middle of the room for their personal meeting for an hour+ just gets in the way.
If this is a common area being used up daily for an hour, or even two- unless this is affecting you, is this actually a problem? Unless there's a scheduled activity you need the space for, is this actually a problem?
How can I ask them not to do this?
Like you would with any other person- reasonably, fairly and politely. But first, ask yourself- do I have to? as a lot of this seems to be more down to you being uncomfortable with the shared living arrangements with people that don't speak English rather than an actual "issue".
I would also like them to try to be a bit more discreet in the sense it's not very comfortable sitting down to eat dinner beside a couple who appear to be having a business meeting.
It doesn't matter what they're doing, if you're eating Dinner at the same time each day while they do this you have two options- either change the time you have dinner, or speak with them about possibly altering the time they do this activity.
Appearances can be decieving, could it not be that they're talking with friends and family? Bear in mind that from their view, if it's actually that- it could be the only time of day they can speak to them- see both sides of the story here.
I tried bringing up the subject by saying "what are you watching" and they replied "why" (which btw I find rude) and I said "curious" and they said "a YouTube video"
From their point of view, someone who doesn't speak their language who could well appear generally irritated at them in general who then starts for all intents and purposes poking their nose in, you would be the one who is coming over as rude.
In my old home sometimes roommates would put on music in the kitchen but I guess this is different because everyone enjoyed it without speaking the language and it wasn't done excessively.
I refer you back to the very first thing I quoted- you are living somewhere with people that are, apparently, predominantly not speaking English, they are internationally diverse. You can't expect people from other countries, with other languages, to necessarily co-habit somewhere without some friction unless you deploy some understanding and a reasonable attitude towards it.
I find since they are speaking a language I don't understand I don't want to interrupt at a bad moment or be insensitive, since they could potentially be discussing something very serious or sensitive.
It doesn't matter if they're discussing private, personal and delicate things or just waht they had for breakfast- the important thing is from how you've phrased things, it is coming over as you being very insensitive.
You need to modify your expectations of living with international tenants if you want to continue living where you are comfortably, you also need to speak with them and in a way that is fair and understanding.
So far it's come over very much as though you are offended that they choose to speak their own language when not talking to you- which let's face it, is rude of you. If you're intolerant of it, then you need to consider somewhere else to stay- if this isn't possible, you need to alter your attitude or learn to tolerate it more.
Unless there's a regular, unfair and loud use of space in common areas and the conditions are such that you feel you can't reasonably relax in your own room, you don't have much of a case here for being upset. All of this can be resolved by speaking with the other tenants- it doesn't need to even bear thinking of the landlord in this equation unless the tenants are being deliberately unfair on you.