You have stocking issues that need looking at, as much as all appears well in that video...
Having 2 Ctenopoma is a very bad number, one will bully the other as they get older, quite possibly to the point of death. Far safer to have a singleton or 4+, I'm a little concerned as I lost one of my 4 in December, but mine are in a 6-foot of African oddballs (so they have room to get away from each other and besides, adding new Ctenopoma to an existing mature hierarchy is rather risky). Your two look quite small (<5cm), so you should either get a couple more ASAP or rehome one.
You do not have a Celebes Halfbeak, sadly most stores import all halfbeaks under that name. There are several species that look quite similar, take a look at Neale Monk's page to get an idea of what you are up against Halfbeaks,
http/brackishfaq.webspace.virginmedia.com/Projects/Halfbeaks/halfbeaks.html . I suspect you are keeping this tank at ~27C fro the GBRs, which is probably a bit high for the halfbeak (but be very careful changing the temp, as with water changes of >10% per change, sudden water parameter changes are often fatal). Eventually, as your Ctenopoma mature, they will try the halfbeak for size.
Your plec, if it is indeed a P. gibbiceps, is going to need a far bigger tank such as a 6x2x2.
Corydoras paleatus (Peppered) are really not good choices for tanks that are permanently kept at tropical temps of 24C plus, Corydoras sterbai for example would be a far better choice for a tank set up for GBRs at ~27C. Peppered Corydoras will be "happy as Larry" in an unheated tank in most homes, that sits between ~15-20C for most of the year.
What are the dimensions of this 35g? Given you have stated it is ~2.5 feet (75cm) tall, this tank cannot be very long or wide, they all need something bigger (even the Corydoras should be in at least a 90x30cm footprint tank, everything else should be in at least a 120x30cm footprint tank). Don't leave it too long to upgrade, your fish will get stunted and some of them could suffer stress related illnesses from being kept in too cramped conditions.