Translation:Their husbands stand behind the restaurant.
You give the pronunciation of בעלים as ב with a shva underneath, and that’s a little confusing because the shva can have basically three pronunciations, so I’d like to run through my understanding of them. In biblical Hebrew, the shva can be pronounced as an uh sound, but not in modern Hebrew, so forget that one. The two choices left are to devoice the shva, which is to skip it, or pronounce it as an “e” as in “Yes”. Here, he pronounces “husbands” as “Ha-bealim”. Please correct me if I’m wrong.
Yes, in Modern Hebrew, a Shva under the first letter is among other conditions pronounced [e], if the first letter is a sonorant (ב is) or the second letter is a glottal consonant [ע is], so you are right for two reasons. In Biblical Hebrew you would have a שְׁוָא נָע: habbəʿālîm
Well, a segolate is a noun, whose stem form was originally CVCC- (C = consonant; V = vowel), but when the original semitic case endings were lost, these words developed a prop vowel to avoid the double consonant at the end. An example is מֶ֫לֶךְ king, which was originally מַלְכּ־ [malk-] (you see this stem still in forms like מַלְכִּי my king), which became a word of two syllables ['melekh], but retains the stress on its first. These types of nouns form their plural according to the pattern CCaCim, i.e. מְלָכִים. A bit technical and simplified, but it is worthwhile to know this group of nouns well, because they are numerous and behave quite uniformely.
Well, yes, the phrasal verb עָמַד מֵאֲחוֹרֵי (if I can call it that) can mean that too beside its concrete literal meaning, like אֲנִי מַבְטִיהָה, אָבִיךְ וַאֲנִי נַעֲמַד מֵאֲחוֹרַ֫יִךְ בִּמְאַת הָאֲחוּזִים I promise, your father and me will stand behind you one hundred percent or חֲבֵרִים אֲמִתִּיִּים עוֹמְדִים אֶחָד מֵאֲחוֹרֵי הַשֵּׁנִי true friends stand behind one another.